Millionaire businessman Tom Wolf was seeking to fend off a five-term congresswoman and two other rivals to capture the Democratic nomination for Pennsylvania governor after nearly four months of folksy TV ads helped make him the front-runner.

A political unknown until his ads began running in the dead of winter, Wolf poured $10 million of his own money into his ad campaign, making him a household name and giving him an early advantage that his competitors struggled to chip away at.

Voters on Tuesday also were choosing their party nominees for the state's 18 seats in the U.S. House of Representatives, all 203 state House seats and half the 50 state Senate seats.

Before casting her ballot in Jenkintown, U.S. Rep Allyson Schwartz told reporters that she was optimistic about her chances, citing voter enthusiasm and many people excited "about a woman running for governor."

"It's a beautiful day, and a lot of people are going to come out to vote," she said.

Wolf, Schwartz, state Treasurer Rob McCord and former state environmental protection chief Katie McGinty together raised more than $35 million to compete for the nomination to take on Republican Gov. Tom Corbett on Nov. 4.

At the polls in New Cumberland, in central Pennsylvania, Democrat John Kerr said he voted for Wolf because he's "the strongest possible candidate to get rid of Corbett."

"I like his demeanor. I think his literature was so specific - and the rest are a bunch of politicians," he said.

Democrat Donald Lindke also picked Wolf because "I want somebody who can defeat this governor." Tina Dorsey said she cast a vote for McGinty because she was so positive in her campaign, though "she's probably not going to win."

Corbett and his lieutenant governor, Jim Cawley, were unopposed in the primary.

Corbett, elected in 2010 largely on his reputation as the state's corruption-fighting attorney general, has been saddled with low job-approval ratings. When he kicked off his re-election campaign in January, one poll showed that fewer than half of the state's Republicans believed he deserved another term.

Among the reasons cited by Corbett's critics are his nearly $1 billion education spending cut in his first year and his opposition to efforts to impose an extraction tax on Pennsylvania's thriving natural gas industry, which would produce hundreds of millions of dollars for the state.

Despite having no primary opposition, the governor has been running TV ads, including one aimed at Wolf and another that touches on his own unpopularity by saying he didn't go to Harrisburg to make friends but to make tough decisions.

The primary also features a five-way race for the Democratic nomination as lieutenant governor.

In the highest-profile congressional primary, former one-term congresswoman Marjorie Margolies was in a four-way battle for the Democratic nomination to succeed Schwartz in the 13th District, which includes parts of Philadelphia and Montgomery County. Margolies counts Bill and Hillary Clinton as family; her son is married to their daughter Chelsea.

The other candidates are Dr. Valerie Arkoosh, an anesthesiologist who outraised her opponents; state Rep. Brendan Boyle, the only Philadelphia resident in the race; and state Sen. Daylin Leach, a champion of liberal causes.

In the governor's race, Wolf, 65, sought to define himself as the non-politician in the gubernatorial field, although he served as state revenue secretary for nearly two years in Gov. Ed Rendell's administration. He promised that he would be "a different kind of governor" if elected.

He stressed his success in turning around The Wolf Organization, a York building-products company that has been in his family for six decades, as well as his stint as a Peace Corps volunteer in India and his doctorate from the Massachusetts Institute of Technology.

The friendly discussions that marked early debates took on an increasingly negative tone last month.

Schwartz raised questions about a loan that provided nearly half of Wolf's $10 million campaign nest egg and about layoffs that occurred at Wolf's company after he retired from day-to-day control and before he returned to lead it out of potential bankruptcy.

McCord questioned Wolf's relationship with former York Mayor Charlie Robertson, who in 2002 was acquitted of murder in the death of a black woman in the city's 1969 race riots. Wolf said he headed Robertson's 2001 re-election campaign but after Robertson was charged, he helped persuade him to abandon the campaign.

Polls close at 8 p.m.