Mainstream G.O.P. Group to Target Bob Good as It Shifts Mission and Members

The Republican Main Street Partnership, a group that supports center-leaning House Republicans, plans to direct half a million dollars into a bid to defeat Representative Bob Good, a hard-right lawmaker from Virginia, making an unusual push to oust a sitting Republican member of Congress.

The move is notable not just because the group, through its campaign giving arm, is inserting itself into the kind of intramural fight against an incumbent that it typically avoids. It is also striking because the candidate it is backing — John J. McGuire, a former member of the Navy SEALs and an election denier who has pledged fealty to former President Donald J. Trump and promised to bring a “biblical worldview” to Congress — bears so little resemblance to the kind of moderate Republican the Main Street Partnership was founded to support.

The nonprofit, which operates out of a townhouse blocks from the Capitol, has for years raised and spent money to support vulnerable Republicans representing politically competitive districts, including centrist G.O.P. lawmakers with more moderate positions on social issues. Its Capitol Hill headquarters serve as something of a counterweight to the Conservative Partnership Institute, which operates nearby as the nerve center of the right.

But as the Republican Party has veered toward the extreme right, purging itself of what was once a sizable and influential bloc of centrists, the Main Street Partnership has also shed the “moderate” label and changed the nature of its mission. The group has recently expanded its membership to include far more conservatives, and has begun focusing less on centrism and bipartisanship and more on ridding Congress of G.O.P. rebels bent on disrupting legislative business and stoking party divides.

Its decision to wade into the G.O.P. primary in a solidly Republican district in Virginia shows how the organization intends to go on offense against the lawmakers who have played big roles in paralyzing the House and making it difficult for the Republican majority to govern — even if that means elevating a hard-right candidate it would never have supported in the past.

“We are now a group of 90 members who just want to get things done,” said Sarah Chamberlain, the president of the Main Street Partnership. She said the group identified Mr. Good as its first target of this election year because of his unique set of vulnerabilities.