What you need to know about the Pa. midterm elections

HARRISBURG, Pa. (AP/WTXF) -- Pennsylvania voters are in the middle of the national political picture as they prepare to cast ballots in Tuesday's election.

The decisions they'll make Tuesday could affect control of Congress and the future of President Donald Trump's agenda.

They have seven open congressional seats to fill, the most in decades.

In the Legislature, all 203 House seats are up, along with 25 Senate seats. Republicans have commanding majorities in both chambers.

GOVERNOR

Democratic Gov. Tom Wolf is running for a second term against Republican Scott Wagner, a state senator from York County who has made millions in the waste-hauling industry. Wagner served four years in the state Senate before resigning in June.

U.S. SENATE

Four-term Republican U.S. Rep. Lou Barletta is seeking to unseat second-term Democratic U.S. Sen. Bob Casey in Pennsylvania.

Casey is one of 10 Democratic senators running for re-election in states won by President Donald Trump in the 2016 election. He is backed by labor unions, gay-rights organizations and environmental advocacy groups.

Barletta, the former mayor of Hazleton in northeastern Pennsylvania, is backed by business trade associations and anti-abortion groups.

U.S. HOUSE

The most open seats in decades -- seven -- and redrawn district boundaries are combining to create more competitive races than usual.

The state Supreme Court in January threw out the congressional district map Republicans drew in 2011, ruling in a gerrymandering case that it was unconstitutionally drawn to give Republicans an advantage. Races in Tuesday's election are being held within new boundaries drawn by the court's Democratic majority. Under the 2011 map, Republicans won 13 of 18 seats in three straight elections, even as Democrats dominated in statewide elections.

Now, Republicans are expected to lose three open seats around Philadelphia and Allentown.

Incumbent Republicans are in close races, including freshman Brian Fitzpatrick in suburban Philadelphia, three-term Scott Perry in southcentral Pennsylvania and three-term Keith Rothfus in suburban Pittsburgh. Four-term Mike Kelly in northwestern Pennsylvania and freshman Lloyd Smucker in south-central Pennsylvania are under pressure in districts won heavily by Trump.

Third-party groups have spent more than $19 million on the races, according to federal campaign finance records.

GENERAL ASSEMBLY

Commanding Republican margins in both chambers - 121-82 in the House and 34-16 in the Senate, when counting vacancies based on which party last held the seat - are expected to shrink amid a large number of Republican vacancies.

In the House, Democrats have candidates in 20 of the 21 open Republican seats, while the GOP has challengers in just 5 of the 12 Democratic openings. Also feeling pressure are Republican incumbents in suburban Philadelphia and the Pittsburgh area, including House Speaker Mike Turzai of Allegheny County.

All five Senate vacancies are Republican-held seats, including two in suburban Philadelphia and one each based in suburban Pittsburgh, and Blair and York counties.

VOTING

Deadlines to register and get an absentee ballot are past, as is the deadline for civilians to submit an absentee ballot. The number of absentee ballots requested from counties this year is eye-opening: more than 227,000. That's fewer than in recent presidential election years, but much larger than the 138,919 recorded in the midterm election of 2010 and the 96,849 reported in the midterm election of 2014, according to Pennsylvania elections officials.

Slightly more than 8.6 million voters are registered. Of that, 4.1 million are Democrats, almost 3.3 million are Republicans and 1.2 million are independent or registered with a third-party. Turnout in the last two midterm elections was between 40 percent and 50 percent of registered voters.

VOTER INFORMATION & RESOURCES

You can check election results as they come in below. App users click here to see results.