With each presidential election comes the inevitable debate about the convoluted Electoral College system. Now, the country may be close to changing it. States are gradually signing on to a plan that would marginalize the power of the Electoral College and create something resembling a national popular vote.

Here's how it would work: States would agree to give all their electoral votes to whoever gets the most votes nationally, regardless of how their own residents vote. The plan would preserve the Electoral College but would make it much less relevant, since the candidate receiving the most votes nationally would be assured victory. This month, California became the latest state to join a compact that includes seven other states plus the District of Columbia. What does that mean? Let's look at some simple math.

The Electoral College has 538 votes. To win a presidential election, a candidate needs to win just over half of those, or 270. So if states representing 270 electoral votes agree to the plan, they can ensure the popular vote winner becomes president, regardless of what other states do.

California has 55 electoral votes, more than any other state, so when Gov. Jerry Brown signed the plan into law this month, it marked a huge victory for the movement. Today, the states that are on board represent 132 electoral votes, putting the plan almost halfway toward the 270 threshold needed for it to take effect.

The plan may seem complicated, but it's actually more likely to gain traction than a constitutional amendment eliminating the Electoral College altogether. Since the Constitution allows states to appoint electors any way they see fit, supporters believe they can achieve their goal by working exclusively with the states. This year Vermont has also joined the plan, and it's been approved by the state senates of New York and Rhode Island.

The most obvious benefit of the plan is that it would prevent a candidate who lost the popular vote from becoming president, which has happened four times, most recently when George W. Bush defeated Al Gore in 2000. The 2004 election was close too: if just 60,000 Ohio voters had cast ballots for Massachusetts Sen. John Kerry instead of Bush, Kerry would have won the presidency despite Bush's nationwide lead of about 3 million votes.

Perhaps more importantly, the plan would force candidates to stop focusing their campaigns on a handful of battleground states that have populations narrowly divided between Democrats and Republicans. Since the candiate that wins a state gets all its electoral votes -- even if he only wins by a slim margin -- candidates of both parties avoid states that are solidly controlled by one party or the other, since their efforts are unlikely to affect the outcome.

Meanwhile, smaller swing states get more attention from candidates, since even a slim victory would give them all the electoral votes. Huge populations in large states are irrelevant to campaigns, and places like Nevada and Indiana have become more important to candidates than Texas and California. In 2008, more than 98 percent of presidential campaign events and more than 98 percent of campaign spending took place in 15 states representing about a third of the nation's eligible voters, according to the organization FairVote, which endorses a popular vote.

For example, it would be hard to blame a Republican candidate for ignoring California, which has gone blue in the last five elections. Yet John McCain got more votes in California than he did in Alaska, Arkansas, Idaho, Kansas, Mississippi, Montana, North Dakota, South Dakota, Utah, West Virginia and Wyoming combined. Because of the winner-takes-all system, he had nothing to show for the support he got from 5 million Californians. Yet he got 47 electoral votes from a smaller number of supporters in those other states. The new system would make places like California relevant, since its vote totals would play a role in determining the national outcome.

Still, the effort could face challenges. The existing system guarantees even the smallest states at least three electors, which gives their residents a proportionally larger influence than residents of big states. Because most states (33, by Governing's count) have a population below the national average, the effort to modify the existing system could be a tough sell. After all, those states benefit from it, says William G. Ross, a law professor at the Cumberland School of Law in Birmingham who has studied the Electoral College.

Critics of the plan say the existing methods ensure the country's president is a truly national leader who gets support from a geographically broad cross-section of America. If the National Popular Vote's (NPV) policy, the group behind this effort, took effect, candidates may find they get the most bang for their buck by spending time in densely populated metro areas, to the detriment of the more rural parts of the country. Unsurprisingly, this has made the issue a partisan one. Many Republicans oppose the plan, and so far, only states that voted for Barack Obama in 2008 have signed on. "I'm a little doubtful that they can get to the magic number, which I think is a stretch," says G. Terry Madonna, a professor at Franklin & Marshall College in Pennsylvania.

Earlier this summer, Texas Gov. Rick Perry, House Speaker John Boehner and Senate Minority Leader Mitch McConnell signed a letter expressing their opposition to the proposal, arguing that it's an attempt by liberals to put the fate of elections in the hands of just a few populous states. It's clear they're taking the movement seriously. "If just a handful of other states sign onto this scheme, the shape of the U.S. presidential elections could be changed forever," the three wrote. The three of them, and other critics of the plan, argue that the founding fathers carefully chose the Electoral College as the best way to select a president. The existing system maintains federalism -- the delicate balance of power between the federal government and the states -- and ensures small states aren't marginalized.

But supporters of reform note the ugly history of the Electoral College. By basing the number of electors a state was allotted on population, not voter turnout, the founding fathers ensured the South would still get credit for its huge non-voting slave population, and it took away the incentive a state may have to increase its own clout by allowing women to vote.

Vernon Sykes, an Ohio state representative who has previously sponsored NPV legislation, says he believes the Electoral College is an antiquated idea, and that Americans deserve something akin to direct election. "I believe our forefathers were thinking in terms of trying to protect us from ourselves to a certain extent," says Sykes, who is also a political science professor at Kent State University. "They were somewhat elitist."