HARRISBURG — Pennsylvania Democrats for now have a four-way primary contest that will be decided in two months to see who will challenge U.S. Sen. Pat Toomey, as the Republican seeks a second six-year term in the 2016 election. The seat is expected to be crucial to determining control of the U.S. Senate. A look at the candidates:

The incumbentToomey, 53, of suburban Allentown, has the Republican Party unified behind him. He has no primary challenger and reported $9.6 million in his campaign bank account as of Jan. 1.

The DemocratsFour people filed paperwork to appear on the April 26 primary ballot: John Fetterman, Katie McGinty, Joe Sestak and Joe Vodvarka.Sestak, 64, is returning for a rematch with Toomey. Sestak was a second-term congressman from Delaware County — and the highest-ranking military officer ever elected to Congress — when he ran for Senate the first time. The former Navy vice admiral lost to Toomey by 2 percentage points in 2010.McGinty, 52, has served in senior posts in both the state and federal government, and in the process forged ties with the Clintons, former Gov. Ed Rendell and sitting Gov. Tom Wolf. In 2014, she ran unsuccessfully for governor in the four-way Democratic Party primary.Fetterman, 46, is the mayor of Braddock, a tiny steel town outside Pittsburgh, and his irreverent and unconventional style has made him a national media darling. After a stint as an AmeriCorps volunteer, Fetterman became mayor in 2006 of the impoverished town, where one in three residents lives below the poverty line.Vodvarka, 72, is making his third run for U.S. Senate. He is a semi-retired owner of a spring manufacturing shop in the Pittsburgh suburb of Clinton. In 2010, he filed to run for U.S. Senate, but lost a court challenge to his petitions by Sestak. In 2012, he won 19 percent of the primary vote on a shoestring budget and lost to Sen. Bob Casey.

Campaign themesSestak has stressed his 31-year military career, his fluency in foreign policy and his wartime experience. He also has stressed his status as a maverick who is not beholden to party leaders.Fetterman stressed his solidarity with the African-American community. He has previously said that he has done more to strengthen the middle class than his competitors and on Friday night, he repeatedly advocated for a $15 an hour minimum wage.McGinty would be the first woman elected to the U.S. Senate from Pennsylvania. She stresses her solidarity with the middle class and on Friday night, she said, “I am in this race to fight for people, to fight for families, the middle class that is squeezed in this country now to the point of near non-existence.”Vodvarka, the son of a late blue-collar union leader, is running on the issue of trade and slapping tariffs on cheap, international imports to bring manufacturing jobs back to the United States. He says he wants the Democratic Party to go back to its roots as “the working man’s party.”

Campaign financeSestak leads the Democratic field. As of Dec. 31, he reported $2.6 million in his campaign account. McGinty reported $1.2 million, Fetterman reported $131,000 and Vodvarka reported $176.