Democrat Conor Lamb, who looks poised to win Tuesday's close special election in Pennsylvania, is positioning himself to run against GOP Rep. Keith Rothfus Keith James RothfusCNN's Tapper tried to talk GOP candidate out of running against Democratic incumbent: report Lobbying world Conor Lamb gets 2020 challenger touted by Trump MORE in another district in November.

Lamb has declared victory in his Tuesday special election in a district under old congressional lines that were invalidated by the state Supreme Court last year.

But the 18th District, where Lamb faced off against Republican Rick Saccone, won't exist under the Supreme Court's new map, so Lamb needs to decide where to run for reelection before next week's petition filing deadline.

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Lamb had been expected to run in the new 17th District, which features a moderate electorate, but had not yet tipped his hand.

But Beaver County Democratic Committee chairman Steve Dupree confirmed to The Hill that Lamb is scheduled to appear at a local Democratic Party event to seek its endorsement for the 17th District.

"He’s got a lot of advantages and some disadvantages," Dupree told The Hill. "He's got to introduce himself to the people of Beaver County. But he has a great ground game and a lot of financial support, which will be very helpful in getting out his message in working together on our commonalities."

The Beaver County Times first reported the news.

But both candidates have to move forward in preparing for the May special election and file petitions with the state by next week.

Saccone has already begun to collect petitions for a new district to the south of Pittsburgh that will include the majority of the old 18th District. But while Lamb had said he would be running for a full term in November, he hadn't explicitly announced where he would run.

"You have to concentrate on what the differences are," Rothfus said. "When you have Conor Lamb come out a couple of weeks ago, and express opposition to a bill that would protect unborn children after 20 weeks, that is very troubling."