The nation's top-elected Republican is flexing some political muscle in Pennsylvania.

House Speaker Paul Ryan was on the campaign trail Thursday for two Republicans who are running to represent parts of Berks County in Congress next year.

"I want to celebrate and thank Ryan Costello for being a really good, hardworking, conscientious congressman," Ryan said.

The House speaker was singing Costello's praises at J-Tech in Chester County. He said, although the congressman who represents parts of Berks has only been in office a short time, he has already pushed a huge transportation bill across the line.

"It's really important that, if we are going to rebuild the infrastructure in our country, that we give localities, municipalities, states time to plan," he said. "This is why it was important that Ryan and his committee got a five-year bill so that you can make long-term planning, so that we can get these jobs back on the road. We can fix our infrastructure."

Costello is up for re-election in Pennsylvania's 6th Congressional District. He's running against Democrat Mike Parrish.

Experts said, although the incumbent usually has the advantage, since it's also a presidential election year, anything can happen.

"In a presidential year in particular, if the Democrats are going to pick up the seats, it's going to be in a presidential year, because voter turnout is higher than in a midterm election, and that typically helps Democrats," said Michael Armato, an assistant professor of political science at Albright College in Reading.

The speaker also made a stop in Lancaster County in support of Pennsylvania state Sen. Lloyd Smucker. He's running against Democrat Christine Hartman for the open seat in the state's 16th Congressional District, which includes Reading.

Ryan will head back to his home state of Wisconsin this weekend to campaign with Donald Trump and other Republicans.