Rosy prospects have attracted a crowded field for Tuesday’s primary. The front-runner is Tom Wolf, a businessman from southern Pennsylvania’s York County who gained early advantage by flooding key media markets with ads before his opponents got their footing. Wolf’s main challenger is Rep. Allyson Schwartz, whose district covers part of Philadelphia and its northern suburbs. As recently as last year, political observers said her unstinting support for abortion rights, including her time as a director of the Elizabeth Blackwell Women’s Health Center, a reproductive health clinic, meant she was too liberal to win a statewide political race.

PHILADELPHIA — Pennsylvania Republican Gov. Tom Corbett swept into office in 2010 on a platform of balancing the budget without raising taxes. Four years later, frustrations with his policies and style have emboldened a field of Democratic challengers eager to prove their liberal bona fides. Many are predicting this year will be tough for Democrats, but in politically mixed Pennsylvania, the party is expecting big things come November.

In a March primary forum in Philadelphia , candidates said they would reinstate the general assistance program, a state cash welfare system that Corbett eliminated . Wolf was not present, but his spokesman Mark Nicastre assured Al Jazeera that if elected, Wolf “would work to re-establish General assistance.”

The Democratic challengers back a funding formula to ensure state aid for education goes where it is most needed. They have all promoted greater transparency for charter schools and want to return the Philadelphia School District to local control .

Despite a recent poll showing that only 39 percent of Pennsylvanians hold a favorable view of the Affordable Care Act, all the Democratic candidates have repeatedly expressed their support for the law. All promise to accept federal money for the expansion of Medicaid, a policy Corbett rejected in favor of his own proposal to insure eligible Pennsylvanians through private companies.

The candidates, who also include former State Treasurer Rob McCord and former state Secretary of Environmental Protection Kathleen McGinty, have all expressed support for taxing natural-gas companies , decriminalizing marijuana, restoring education spending, raising the minimum wage and strengthening the state’s safety net.

But in this primary, progressive activists have attacked her record on aspects of the Affordable Care Act and support for cuts in Social Security. As the primary heated up, Schwartz severed her ties to Third Way, a centrist think tank for which she had served as an honorary co-chair.

Rep. Allyson Schwartz was just a few years ago seen by Democratic insiders as too liberal to win a statewide race. AP

He’s in the worst shape of any governor seeking re-election in the modern history in this state.

The leftward tilt of the Democratic field has been tied, in part, to the deep unpopularity of the incumbent governor. Corbett’s approval ratings have crept above 50 percent only once since 2011, and a late February poll showed him losing to Wolf 52 to 36 percent. No Pennsylvania governor has lost a re-election campaign since the state constitution was changed in 1968 to allow two consecutive terms, but that could soon change.

“He’s in the worst shape of any governor seeking re-election in the modern history in this state,” says Terry Madonna, director of the Franklin and Marshall College Poll.

Corbett’s unpopularity is due, in part, to an inability to energize the conservative movement while governing too far to the right for many Pennsylvanians. “I don’t know if he was bold enough for his supporters, but he was still perceived by many other voters as being too conservative,” says John J. Kennedy, a political science professor at West Chester University and the author of “Pennsylvania Elections: Statewide Contests From 1950–2004.” “You would probably have to go back to Ed Martin in 1942 to find a more conservative Republican governor.”

Corbett focused on balancing the budget without raising taxes — making massive cuts in education and social services during his first two years in office. The state’s share of public-school funding fell from 44 to 34 percent, forcing local voters to choose higher property taxes, a decrease in school services or both.

“Education is the single most important issue in this campaign, and that’s the first time that’s been the case in Pennsylvania,” says Madonna, whose team released an analysis last year showing that Pennsylvanians were more concerned about education than unemployment for the first time since 2010. A May 1 poll from Muhlenberg College also found that education is the No. 1 issue.

“The big mistake the governor made early in his administration was underfunding public education across the board,” says the Rev. Mark Tyler of the Mother Bethel A.M.E. Church in Philadelphia. “In the same budget he provided funding for new prison construction. That really sent a clear message about where the priorities for that administration were going to be.”

Corbett’s policies also included tuition increases for state universities and colleges, cuts in the number of Medicaid recipients and reductions in county human-services and mental-health programs.

Corbett has lost support among conservatives too. His biggest policy accomplishment last year was a transportation bill aimed at helping repair the state’s roads and rails by increasing the gasoline tax and other fees — hardly the kind of thing to gin up the conservative base. In a January poll, only a third of Republicans thought Corbett was doing a good job.

“I’ve never heard a good word about him from either side of the aisle,” says Bryan Driesbach, who works for the United Steelworkers in the region around Reading, Pa. “I have a bunch of Republicans in my family, and they all want him gone too. That 10 cent tax he just added to the gasoline, and then he’s handing out tax breaks to Shell and the fracking companies? That’s rubbing a lot of people the wrong way.”

Corbett’s frequent missteps have also hurt his standing among voters. Last year he compared same-sex marriage to marriage between siblings during an apology for a subordinate’s comparison to marriage between children — this at a time when a Franklin and Marshall poll showed a majority of Pennsylvanians are in favor of gay marriage for the first time. In January he abandoned his only visit to a Philadelphia public school at the last minute in favor of a press conference in the city’s Chamber of Commerce.

But it is Corbett’s policy priorities that seem to have put him noticeably out of step with a changing state.

“In the western part of Pennsylvania, past the Susquehanna River, a lot of old mining and mill towns tend to be culturally conservative. But they have lost population,” says Madonna. “The real growth of our state is in the [increasingly liberal Democratic] Philadelphia suburbs and in the Lehigh Valley. There’s a big transition underway.”

On Tuesday, Corbett’s Democratic challengers hope to capitalize on that transition.