When state attorneys general agreed on a landmark settlement with tobacco companies in 1997, all they needed to finish the deal was approval from Congress. But Washington, D.C.'s powerbrokers balked at taking orders from the states' chief legal officers. "Who do these people think they are?" Sen. John McCain wondered.

Over the last 13 years, it's become quite clear who state AGs think they are. The tobacco settlement, finalized in 1998 with tens of billions of dollars in payments to states, was just the beginning. State AGs continued asserting themselves on a national level as the scourges of corporate bad guys and the guardians of consumer interests. In 1997, the national influence of state AGs seemed novel. Today it doesn't.

Yet many Democrats in Washington now are asking the same question as McCain: "Who do these people think they are?" That's because the powerful people state AGs are confronting aren't just in corporate boardrooms--they're in the White House and the U.S. Capitol. In the last few months, conservative AGs have become some of the nation's most prominent opponents of federal power in general and the Obama administration specifically. They're trying to block provisions of the federal health-care reform law in court, and they're working to limit the federal government's power to regulate guns and greenhouse gas emissions.

On the surface, these actions look like another reimagining of the state AGs' role. The tobacco settlement created a model for activism for a liberal Democratic AG. Perhaps then, conservative Republican AGs, with their states' rights stands, are developing their own model as to how to affect the nation's most important policy decisions.

But it's probably more accurate to say that the Republicans are developing a new twist on older models. After all, AGs of both parties long have fought to protect state prerogatives. Nor are today's Republican AGs the first to engage in a politically charged battle with a president of the opposite party. Democrats did the same thing to George W. Bush over environmental regulation.

New model or not, one thing is clear: Almost overnight, some of the country's most important, controversial politicians are Republican AGs. They can attribute their new clout to the presence of a Democrat in the White House.

After the tobacco settlement, AGs became stars--well, some of them anyway. Connecticut's Richard Blumenthal made a name for himself as a scourge of health maintenance organizations, insurance companies and power plants. California's Bill Lockyer sued car companies for auto emissions. Most famously, New York's Eliot Spitzer cracked down on the excesses of Wall Street.

Blumenthal, Lockyer and Spitzer are all Democrats. It took two years for the first Republican AG to join Democrats in their suits against tobacco. Most of the AGs who engaged in a major anti-trust case against Microsoft in the late 1990s also were Democrats.

It's not as though Republicans completely stayed on the sidelines. Most Republican AGs eventually participated in tobacco suits. And Republicans generally have been as happy as the Democrats to become involved in consumer protection cases. But with business groups complaining that the Democratic activists were bullies who overstepped their roles as state officials, Republican AGs never quite embraced the model that Spitzer and others refined. Conservatives didn't want to be anti-business or favor excessive regulation.

In fact, some conservative AGs, led by Alabama's Bill Pryor, actively rebelled against this model. But Pryor and his ideological compatriots largely were defined by what they weren't: activists in the Spitzer mold. Most Republican AGs weren't having a national impact in the way that some of their Democratic counterparts were. They didn't seem to have a coherent, common national purpose.

In that context, it's surprising how easily Rob McKenna, Washington state's Republican AG, articulates just such a purpose. "The role of the attorney general," McKenna says, "is to be a guardian of federalism and to protect state prerogatives."

For Republican AGs, protecting state prerogatives has meant battling the Obama administration and Democrats in Congress. In doing so, they've enjoyed instant influence.

When the Senate passed a version of health-care reform that included special Medicaid payments to Nebraska--the so-called "Cornhusker Kickback"--13 Republican AGs wrote to Congress threatening to sue, claiming their states weren't being treated equitably. Congress dropped the provision. Later, Democratic leaders in the House of Representatives considered using a procedure know as "deem-and-pass" to allow the House to give approval to the unpopular Senate version of health-care reform without a direct vote on the matter. Republican AGs threatened to sue again, arguing deem-and-pass was unconstitutional. The House dropped the strategy.

Those concessions, of course, didn't stop AGs from suing when Obama finally signed the health-care bill into law in March. The AGs argue that requiring everyone to buy health insurance is unconstitutional and that the law places an unfair burden on the states. So far, around 20 states are supporting legal action to block the law, and all but one of the participating AGs are Republicans.

Health-care reform is the most obvious example of the Republican activism, but it's not the only one. A group of Republican AGs and a few Democrats from energy-producing states also teamed up to try to prevent the federal Environmental Protection Agency (EPA) from regulating greenhouse gas emissions. Eight AGs--five Republicans and three Democrats--from conservative states are arguing in court that federal gun regulations shouldn't apply to firearms made and sold within their borders. "There is a sense now among conservative attorneys general that this position could be used creatively and aggressively to pursue conservative ends," says James Tierney, a former Maine AG who directs Columbia Law School's National State Attorneys General Program.

Among the Republican AGs, none has proven himself to be more aggressive--or more conservative--than Virginia's Ken Cuccinelli. Cuccinelli, a global warming skeptic, took the lead challenging the EPA over greenhouse gas regulations and now is challenging the EPA over new automobile fuel economy standards. Mere minutes after Obama signed the health-care reform bill, Cuccinelli filed a challenge to it that was separate from other states, arguing that a Virginia law prohibiting a health insurance mandate should supersede the federal law.

Cuccinelli also has created controversy back home. He wrote a letter to public colleges and universities telling them they couldn't bar discrimination on the basis of sexual orientation. He's demanding documents from the University of Virginia on a former faculty member's research, saying it might reveal the scientist's work on climate change to be fraudulent.

The end result is that Cuccinelli is a darling of the right and a villain to the left. He is perhaps as famous as Spitzer in his heyday. He's clearly just as polarizing. The remarkable thing: Cuccinelli took office just five months ago.

Other Republican AGs who also have been quite active, such as South Carolina's Henry McMaster and Texas' Greg Abbott, haven't become as famous. But even if they're not household names, what they're doing is national news. Democratic AGs now are the ones on the defensive. In conservative states such as Oklahoma, Arkansas and Georgia, Democrats have faced--and resisted--pressure to join the health-care suit.

While Cuccinelli is the person most closely linked to the states' rights revival, the state with the most enthusiasm for it is Utah. There, Republican Attorney General Mark Shurtleff has been an eager participant, though he hasn't completely had a choice in the matter: The Utah Legislature has demanded that he take on the federal government.

The legislature approved a resolution asserting the state's sovereignty under the Constitution's 10th Amendment. It passed a bill to opt out of federal gun regulations, setting up Shurtleff's participation in that issue. It even approved legislation directing Shurtleff to try to use eminent domain on federal lands to claim them for development.

The situation in Utah highlights one reason conservative AGs are becoming so prominent. Conservative legislators and governors are engaged in their own rebellion against the Obama administration. As states' legal officers, AGs logically are becoming some of the faces of this movement.

So is Shurtleff celebrating his brand new sense of purpose? Well, no. "This isn't new for me," he says.

Shurtleff notes that Utah long has had a fondness for fighting the federal government. He points out that early in his term, he was battling with the George W. Bush administration over federal land issues. "I said, 'I don't want to sue my new Republican president, but it's states' rights,'" Shurtleff says.

Utah isn't unique. Western states have battled Washington over federal lands for years. AGs have been the forefront of these battles--and other ones with the feds. "States and their lawyers have long been suspicious of federal power," Tierney says. "That's why we have federalism. It would be unnatural for states not to protect themselves within the federal system."

Most of these fights are bipartisan. Almost every AG supported New York as it worked to preserve states' right to enforce their own lending laws. In 2009, the Supreme Court sided with the states.

Almost every AG teamed up again to ask the Obama administration to support ending federal pre-emption of state banking regulation in this year's financial reform legislation. The White House agreed. Tom Miller, Iowa's longtime Democratic attorney general, says financial reform shows the real story--it isn't that AGs are battling the White House more; they're actually battling it less.

"My view," he says, "is that the litigation against the federal government is the exception. Overall, the attorneys general have the best relationship with the Department of Justice in decades. That includes Democrats and Republicans."

But if health-care reform is an exception, it's an awfully big one. Obama has won approval of the most far-reaching domestic legislation under any Democratic president since Lyndon Johnson. The last people standing in the way from it becoming a reality aren't in Washington, D.C.; they're attorneys general in the states.

In principle, AGs may agree on defending states against federal power, but in this case they're divided. A group of Democratic AGs plan to submit their own brief defending the constitutionality of the health-care law.

The question is whether this divide is a sign of things to come. Sure, people such as Shurtleff have been fighting the feds for a long time, but the prominence of conservative AGs in the health-care debate wasn't quite like anything that's happened previously. Over the long term, will conservative AGs become more aggressive in trying to check the grandest ambitions of the federal government?

Michael Greve, a federalism expert at the conservative American Enterprise Institute, has an interesting answer to that question: They shouldn't want to.

Greve's point is that limited government and reduced regulation--key conservative goals--aren't served by devolving power to the states. "It is a conceit and mistake on the part of Republicans to think that decentralization translates into smaller government," he says. "If you really wanted to form an effective coalition in favor of a deregulatory agenda, you'd have to oppose states that are on the pro-regulatory side."

If you look back at the role that Democratic AGs played during the Bush administration, you can see what Greve means. Liberal AGs fought for states to be allowed to set tougher auto emissions standards than the federal government. During the Bush years, more state power would have meant more stringent environmental regulation. That probably will be true again during the next Republican presidency. If conservative AGs were to fight for more state power regardless of who is in the White House, they'd end up doing so at the expense of conservative policy objectives.

But at least with regard to environmental rules, conservative AGs weren't fighting federal power under Bush. Instead, liberal AGs were. They didn't just ask to set their own emissions rules. They sued to force the Bush EPA to treat greenhouse gases as pollutants--and won before the Supreme Court.

On the policy question--whether there should be more or less environmental regulation--the two sets of AGs have been completely consistent over the last two presidencies. But on the federalism question--how much power the federal government should have to design whatever environmental policies it wants--they've flipped. Democratic AGs wanted to constrict federal power under Bush. Republican AGs want to do it now.

That's why Tierney gives a pithy answer to the question of whether conservative AGs are doing something new by fighting Obama. "It's only new," he says, "because conservatives are doing what liberals did before." Maybe Republican AGs now are so committed to fighting the feds that they'll become prominent foes of the next Republican president too, but if so, that would be something truly new.

If, instead, the precedent set in the last two presidencies continues, then the influence of Republican AGs over national policy is likely to wane the next time a Republican is elected president. With a Republican in the White House, it will be Democrats' turn to battle the federal government--and to become the new political stars.