WASHINGTON — President Trump will head to northern Pennsylvania for a campaign rally next week as he looks to shore up his support in a key battleground state for his reelection bid, as well as give a boost to the GOP's chances in a House special election. 

Trump will hold the rally at an airport hanger in Montoursville, the campaign announced on Monday, his seventh rally in northeast Pennsylvania, according to the campaign's count. 

The event comes just one day before the special election in the state's 12th Congressional District. 

Republican Fred Keller, whom Trump endorsed a few weeks ago, is expected to win the seat vacated by former GOP Rep. Tom Marino. Marino resigned just two weeks into his new term this past January. 

The district is heavily Republican — a New York Times analysis of the newly-redistricted district estimates that Trump won it by 36 percentage points in 2016. 

Democrat Marc Friedenberg, a Penn State professor, is running against Keller.