WASHINGTON — In a shake-up for two statewide races, Main Line Republican Jeff Bartos is dropping out of Pennsylvania's U.S. Senate race and joining the gubernatorial ticket of State Sen. Scott Wagner, according to three Pennsylvania GOP sources.

A formal announcement is expected Thursday.

Bartos will run as Wagner's lieutenant governor candidate. His decision removes the main obstacle for U.S. Rep. Lou Barletta on his path to the Republican nomination for the Senate.

Barletta and Bartos had been the two most active figures among a handful of Republicans vying for the chance to challenge the incumbent senator, Democrat Bob Casey, next year.

For Bartos, he stands a better chance at winning elected office with Wagner after being boxed out of the Senate primary by Barletta, a close ally of President Trump who is likely to secure the bulk of the party's organizational support.

Wagner, a York County Republican hoping to take on Gov. Wolf, benefits by strengthening his ticket, boxing out primary rival Paul Mango — a western Pennsylvania businessman — and another potential contender, Mike Turzai, the speaker of the state House.

Bartos could not be reached Wednesday, but several Republicans familiar with the plan confirmed his approach. Wagner did not immediately respond to a request for comment. But he posted on Facebook Monday that a "big announcement" would be "coming soon."

The party sources spoke on condition of anonymity because they did not want to be named pre-empting a formal announcement.

Wagner has long fashioned himself as an anti-establishment candidate, winning his state Senate seat in a 2014 write-in campaign for a special election and serving as an early booster in 2016 for President Trump's campaign in Pennsylvania.

Bartos, a real estate executive from Lower Merion who has never run for office, has ties to the state's Republican establishment, having served on the board of a political action committee headed by Bob Asher, a Republican National Committee member from Montgomery County.

But he declared himself a political "outsider" in his campaign and attacked Barletta and Casey as career politicians.

Like Wagner, Bartos has not been shy about dipping into his own pocket for campaign expenses. He had just over $1 million in his Senate political action committee as of Sept. 30, more than half from loans to the PAC, according to a campaign finance report filed Oct. 13.

Bartos made two personal loans, totaling $550,000, in June and September.

What becomes of that money could say a lot about the new Wagner-Bartos partnership.  Federal and state campaign finance laws make it easy to move money from federal PACs, which operate under contribution limits, to statewide PACs, which do not. It is far more difficult to move money in the other direction.

Last month, Bartos wrote on Breitbart, a right-wing news site run by former Trump adviser Steve Bannon, that he "will not pledge" to back U.S. Sen. Mitch McConnell, the Kentucky Republican who serves as majority leader.

McConnell is a popular target for Bannon and like-minded anti-establishment political activists on the right.

With Bartos out of the Senate race, several other Republicans are challenging Barletta for the nomination: Paul Addis, State Rep. Jim Christiana, Bobby Lawrence, Cynthia E. Ayers, and Joseph Vodvarka.