There's an old saying in American politics that every senator wakes up in the morning and sees a president in the mirror.
That sort of ambition is also common among governors.
The Republican field is led by former Florida Gov. Jeb Bush and current Wisconsin Gov. Scott Walker. In fact, no fewer than a dozen governors and ex-governors are listed among the potential Republican candidates by the Crystal Ball, a political prognostication site sponsored by the University of Virginia.
Prior to the election of former Sen. Barack Obama in 2008, four of the previous five presidents had been governors.
"It helps to be a governor," said David Yepsen, director of the Paul Simon Public Policy Institute at Southern Illinois University. "The reason is that people are looking for executive experience, and they're looking for executive demeanor -- can-do, take-charge individuals."
The Democratic field is dominated by Hillary Clinton, a former senator and secretary of state. But Martin O'Malley, the former governor of Maryland, also seems likely to run.
"Being governor is more like being president than is the job of being senator," said John Weingart, director of the Center on the American Governor at Rutgers University. "You don't have to vote on hundreds or thousands of issues that could be used to attack you during the presidential campaign."
None of this is a guarantee that a governor will be the next president, or even the nominee of either major party. Governors may not have an extensive voting record, but they are judged by their performance.
That can be a positive, but governors with big ambitions find their careers newly scrutinized by a national press corps searching for flaws. Chris Christie of New Jersey, just to cite one example, has received a great deal of negative press lately due to a judge tossing out his package of pension cuts, allegations of cronyism, and the infamous George Washington Bridge incident of 2013.
In addition, governors typically lack experience with defense and foreign policy issues. Walker, while a hero on the right for taking on public-sector unions in Wisconsin, has stumbled when asked questions about the rest of the world.
ISIS and Iran will move foreign affairs higher on the radar of voters than they were back in 2012.
"To the extent that foreign policy and national security continue to be at or near the top of the issue mix, there clearly is an advantage for someone who is a senator, particularly a senator who has been deeply involved in foreign affairs," said Whit Ayres, a GOP consultant whose firm is working with two senators, Marco Rubio and Lindsey Graham, on their presidential explorations.
But not being seen as a creature of Washington is a big advantage right now. An astonishingly low 5 percent of Americans have a "great deal of confidence" in Congress, according to a recent survey by NORC, an independent research organization at the University of Chicago.
"For Republicans, who seem to be intent on who can be the most critical of Barack Obama and most different than Barack Obama, a few years as governors may be more attractive to primary voters than a couple of years or couple of terms in the Senate," said Weingart, the Rutgers professor.
Governors haven't always been top candidates. Prior to the election of Jimmy Carter in 1976, no former governor had made it to the White House since Franklin D. Roosevelt, who won his first term in 1932.
The switch in the 1970s by the two major parties to picking most delegates through primaries may have helped governors, since they don't hold as much of an insider position within their parties as senators, suggested Kyle Kondik, managing editor of the Crystal Ball. "As governors they were further away from Washington," he said.
The large and open field on the Republican side gives governors an opening. Kondik noted that senators such as Rubio, Ted Cruz and Rand Paul have all managed in one way or another to do something to alienate important constituencies within the Republican Party.
"It's not like being a governor totally insulates you from doing things that may have upset members of your own party," Kondik said, "but it's not as obvious as when you're a senator."
Bush and Walker are pacing the field right now, but there's a long way and many missteps yet to go before Iowa and New Hampshire voters have their say (let alone the rest of the country).
"When it comes to selecting a president, people are going to make up their minds based on the person involved, their strengths and witnesses, not whether they come from a state capital," said Ayres, the consultant.
In the coming weeks, Governing will be examining the records of the governors poised to run for president in 2016.