PORTLAND, Maine (AP) — The Democratic primary to take on Republican Sen. Susan Collins of Maine was shaken up Wednesday by the decision of one candidate to drop out and join a different race with similarly high stakes.

In a move that could have implications for the closely divided U.S. House as well as the Senate, Jordan Wood, a onetime chief of staff to former U.S. Rep. Katie Porter, D-Calif., withdrew from the Senate race to seek the congressional seat representing Maine’s 2nd Congressional District, where incumbent Democratic U.S. Rep. Jared Golden recently announced that he will not seek another term.

That leaves Gov. Janet Mills, a party mainstay, and Graham Platner, an oyster farmer who has gained attention for progressive views and provocative online posts, as the top Democratic challengers to Collins.

Wood’s announcement sets up a potential Democratic congressional primary in the key 2nd district with former Secretary of State Matt Dunlap. The leading Republican candidate for the House seat is former Gov. Paul LePage.

“After many conversations with my family and voters in Maine’s 2nd Congressional District, I’ve decided to step up and to be the fighter for the district where I was born and raised,” Wood said in a Wednesday statement.

Maine’s upcoming 2nd District and U.S. Senate races are both highly competitive and could help shape the balance of power in Congress. Collins is the sole Republican Senator in New England, and toppling her has long been a Democratic Party goal. Republicans, meanwhile, have prioritized winning back the 2nd District, where President Donald Trump is popular.

Dunlap announced his bid for the 2nd District weeks before Golden’s announcement that he is vacating. Dunlap said in a statement Wednesday that Wood entering the race “doesn’t change our campaign or our commitment” and that he’s “in this to fight for the people of Maine.”

LePage served as governor from 2011 to 2019. He announced his bid for Congress months ago. Brent Littlefield, a LePage spokesperson, said in a statement that Wood is too liberal for the 2nd District.

“Mainers will pick a job creator, Paul LePage, who will grow the economy and push back on high prices,” Littlefield said.

Two other onetime Democratic candidates for the Senate seat, brewery owner Dan Kleban and former Air Force civilian contractor Daira Smith-Rodriguez, recently dropped out and endorsed Mills. A handful of other Democratic hopefuls remain, though only Mills and Platner are campaigning aggressively.