U.S. Rep. Lou Barletta won Pennsylvania's 11th District seat in 2010 in a wave year for Republicans, amid the rise of tea party conservatives and a backlash against President Barack Obama.

Somebody else will win that seat next year, now that Barletta has declared his candidacy for the U.S. Senate. Barletta is running for the GOP nomination to challenge Democratic Sen. Bob Casey, who is seeking a third term in a midterm election that will double as a referendum on President Trump.

The opening Barletta left is already drawing interest.

G. Terry Madonna, director of the Franklin and Marshall College Poll, says the district's demographics favor Republican candidates because of the way its boundaries were redrawn in 2011 to reflect the latest census after Barletta's first victory there.

Barletta was the mayor of Hazleton who had already drawn national attention for his stance on immigration when he won the relatively compact district, about 83 miles wide, running east from Jerseytown to the Delaware River, with a northern peninsula that included Democratic-leaning Scranton.

Now it runs nearly 150 miles on a southwest-to-northeast axis, from Cumberland County in the south to Wyoming County in the north, and carves out Scranton.

Madonna jokes that Barletta's constituents in the southern part of the district are about 50 miles from the Mason-Dixon Line, while those in the north are about 50 miles from the New York border.

"The seat is more likely than not to remain in Republican hands because of the artful gerrymandering," Madonna said. "Because it's an open seat, I'm sure the Democrats will take a look at it and maybe put some resources in."

The only declared candidate in the district, Democrat Alan Howe of Carlisle, doesn't see that happening any time soon.

"This isn't perceived by the Democratic Party as a swing district," said Howe, who served 24 years in the Air Force and declared his candidacy in April. "I don't think the Democratic Party nationally is going to jump aboard until we start showing them we are winning this district."

Dan Meuser, a Luzerne County Republican who was secretary of revenue under Gov. Tom Corbett from 2011 to 2014, said he expects to make a decision "in the next several days" about entering the race. Meuser, who previously served as president of a company that manufactures motorized wheelchairs and scooters, stressed his long-running friendship with Barletta.

"Certainly with the vacancy created, I think it's very important to retain his seat," Meuser said. "I think I'm in a good position to do that."

Jon Anzur, a spokesman for Barletta's Senate campaign, said Barletta is friends with many of the potential Republican candidates for his seat but "hasn't really given much thought to who would succeed him."

Republicans make up 45.7 percent of the voters in the nine-county district, while Democrats hold 40.7 percent and 13.6 percent are independent or members of smaller political parties.

Dennis Wolff, a dairy farmer from Columbia County who served as agriculture secretary under Gov. Ed Rendell from 2003 to 2009, said he is considering a run in the Democratic primary election.

"I think I'm just like a lot of people in the 11th District," Wolff said. "We're frustrated in the dysfunction that Congress has shown in the last few years."

On the Republican side, State Rep. Stephen Bloom of Cumberland County said he is "continuing to explore the possibility" of seeking the 11th District seat. Bloom was first elected to the state House in 2010.

State Rep. Tarah Toohil of Luzerne County, also first elected in 2010, said she, too, is considering a run.

Andrew Lewis, a Dauphin County Republican and executive in his family's drywall business, said he had heard from "many supporters" urging him to run now that Barletta is not seeking the 11th District seat.

"I am thankful for their support, and will be taking some time to talk it over with my family," Lewis said in an email.