It's likely that more incumbent governors will lose their jobs this year than at any time over the past quarter-century.

Since 1990, no more than four incumbent governors have lost in any given election year. Democrat Neil Abercrombie was already defeated in Hawaii's Democratic primary, while Republican Tom Corbett of Pennsylvania is considered a sure loser next week.

In addition, there are nine other incumbents who are either trailing or leading their opponents by less than 5 percentage points, according to polling averages. In addition, party control may switch in open-seat races in Arkansas and Massachusetts.

"It's the national theme," said David Yepsen, director of the Paul Simon Public Policy Institute at Southern Illinois University. "It's not just anti-Obama, but anti-incumbent."

Yepsen notes that a number of the governors up for re-election have brought their troubles on themselves, through mistaken policies or, in some cases, their own personalities. A badly handled snowstorm in Atlanta in January is contributing to Republican Nathan Deal's problems in Georgia, but every governor has his own problems to address.

Most governors running this year will win easily. But many others are in trouble due to dynamics playing out in multiple states, if not any single overriding issue.

For one thing, there's the last election. Republicans did so well in 2010 that they were bound to have some difficulties in states that lean Democratic in presidential voting, including Maine, Michigan, Florida and Wisconsin. That became apparent last year, when Democrat Terry McAuliffe won in Virginia -- a state President Obama carried twice -- breaking the commonwealth's decades-old tradition of electing governors from the party that didn't control the White House.

The last couple of years have been a period of mostly unified control at the state level, with red states and blue states moving aggressively in completely opposite policy directions. It's possible some governors are now in trouble for having signed off on legislation that was either too liberal or too conservative for the state.

Pat Quinn of Illinois, John Hickenlooper of Colorado and Dan Malloy of Connecticut, all Democrats in extremely tight races, signed off on various combinations of tax increases, environmental protections and gun control that proved unpopular with some portion of their constituents.

Conversely, the attacks on unions from Republicans Scott Walker in Wisconsin and Rick Snyder in Michigan, as well as the large tax and spending cuts pushed by Sam Brownback in Kansas, turned out to be polarizing.

Although he is running for the U.S. Senate, House Speaker Thom Tillis of North Carolina arguably belongs in this polarizing category, since the conservative legislation he helped pass appears to be a major reason he's been struggling more than most of the GOP's Senate prospects this year.

Aside from the question of whether governors pushed ideological agendas farther than voters could support, there's also the general mood of the country. This class of governors has been in office during a time of cutbacks for state government. The economy has been improving, but not enough to make many Americans feel confident.

"It's a sign the recovery has not settled into the bones of the American people," said Charles Zelden, a professor of history, law and politics at Nova Southeastern University in Florida. "There's still a lot of unhappiness, and they're taking it out on the executives of the states."

As Zelden notes, some of these governors made promises it turned out they couldn't keep. Walker in Wisconsin, for example, pledged to create 250,000 jobs. There are only about 110,000 more private-sector jobs in the state than when he was sworn in. The fact that he fell far short of his goal is something on which his Democratic opponent, Mary Burke, has focused.

Meanwhile, voters are not getting as much out of state government as they'd come to expect. With at least 30 states providing less per-pupil funding for K-12 schools than they did before the recession, it's not a surprise that education spending has been a central issue in several of the races for governor. "It's been a time of retrenchment in state government," said Kyle Kondik, an elections analyist at the University of Virginia's Center for Politics. "There have been a lot of cuts."

Given lingering unhappiness with the economy and the performance of state government, voters appear to be in a mood that is more anti-incumbent than anything. Not all these governors are going to lose. Those that do, may lose by tight enough margins that there's a danger in reading too much into the question of what sort of message voters were trying to send.

But something is making voters uncomfortable. In a year when more incumbents are running than at any time since the 1960s, more gubernatorial contests than usual are competitive.

"Part of this just has to do with this sense that some of the people who are running things are either incompetent or out of touch," said Lara Brown, a George Washington University political scientist. "In a two-party system, your own real opportunity is to vote for the other party."