Other candidates are former U.S. Rep. Mark Critz of Cambria County, Harrisburg City Councilman Brad Koplinski, Bradford County Commissioner Mark Smith, and State Sen. Michael J. Stack of Philadelphia. The winner will join the Democratic nominee for governor and face Gov. Corbett and Lt. Gov. Jim Cawley in November.
As the governor's second-in-command, the lieutenant governor serves as president of the state Senate, and casts tiebreaking votes. The officeholder also sits on the state Emergency Management Commission, chairs the Board of Pardons, and draws a $157,765 salary.
If the governor resigns or otherwise must vacate the office, it's up to the lieutenant to step in - something that has happened twice in the last two decades. Mark Schweicker became governor after Gov. Tom Ridge was tapped to run the nation's Office of Homeland Security in 2001, and Mark Singel served as acting governor for six months when Gov. Robert Casey underwent a heart-liver transplant in 1992.
Still, public interest is typically low. In 2010, about 210,000 people voted to put Cawley on the Republican ticket - fewer than half the votes Corbett got in the primary.
A survey released this week by Harper Polling, a firm based in Harrisburg, placed Stack first with 20 percent of the vote, 2 percentage points ahead of Critz. But the poll had a 4-point margin of error, and in the survey of 559 likely voters, 42 percent were undecided. Other candidates were polling in single digits.
Here is a look at the candidates:
Stack, 50, has been a senator for 13 years - experience that might account for the money pouring in to his campaign. Stack has raised more than $700,000, more than twice that of any of his opponents.
Stack has focused his campaign on public and higher education, saying he would tax natural-gas companies to fund improvements to schools, as well as raising the minimum wage.
"The current administration doesn't have education and young people as the priority," he said. "I'm hopeful for Pennsylvania's economic future, and I know we can turn things around. But it begins and ends with a new administration."
Stack has sought to portray himself as the race's most politically viable candidate, someone who can use his relationships in Harrisburg to deliver votes in November.
"Corbett can't articulate his vision, he can't generate momentum with people who are willing to carry out his agenda," he said. "When you think about someone who's there to help the governor, who better than someone who has worked with these guys, and has the credibility?"
Critz, 52, also has spent much of his life in politics, having worked for then-U.S. Rep. John P. Murtha (D., Pa.). He was later elected to Murtha's 12th District seat, where he represented Beaver County and parts of other western counties.
In Congress, he said, he worked on bills that he hoped would bring the most direct impact to Pennsylvania residents, such as one aimed at directing natural-gas industry jobs to local employees.
Critz said his travels across Pennsylvania to meet voters have helped him build a strong base for the November election.
"I bring a tool set that can help the governor accomplish almost anything," he said. "My job is to be a teammate, to help move the governor's agenda forward."
Neuman, a lawyer serving his second term in the state House, said he leaned on colleagues to help spread the word of his campaign. He has supported bills to protect whistleblowers and prevent government fraud, championed youth programs, and developed education forums to help students develop skills in science, arts, and technology fields. He said his experience would be an asset to the next governor.
"Those candidates are all running on policy," he said. "When they get to Harrisburg, they'll need help getting things done and making connections with people."
Smith, 36, is serving a second term as chairman of the Bradford County Board of Commissioners. As the youngest to hold the job, and only the second Democrat, he said, he has learned how to work well with members of other parties. He said he also has worked to cut taxes and balance budgets.
As Bradford County became the top county in the state for natural-gas drilling, Smith has been a prominent critic of the Corbett administration. He supports taxing natural-gas companies and has said the next administration must undo environmental damage to the Marcellus Shale.
"I'm very progressive, and very proud of it," he said.
Koplinski, 44, came to Pennsylvania through his work on John Kerry's presidential campaign, and never left. Now a political consultant and a councilman in Harrisburg, he said he has collected signatures from each county in the state. He has spent much of his campaign telling voters he would help build better relationships between Pennsylvania's municipalities and state and federal government agencies, he said.
"Everybody gets it, because their school board just raised taxes, or a sinkhole just opened up down the street," he said. "We talk to municipal officials everywhere we go, and this resonates.
"Politics is about relationships," he added, "and I've been working with people on a statewide level for a long time."