Eric Cantor, the Republican star unexpectedly bounced from the US Congress by a political novice, will step down as House majority leader by the end of July, US media reported Wednesday.
Two Republican congressmen said Cantor was expected to make the announcement to the party caucus at 4:00 pm (2000 GMT). Cantor will address reporters after the conference.
The move sets off a scramble for the number two post in the House Republican leadership, just as lawmakers crank up their campaigns ahead of November's mid-term congressional elections.
Lawmakers have said three names were already circulating as potential Cantor replacements: Kevin McCarthy, who is in line as the chamber's number three Republican; Rules Committee chairman Pete Sessions, and Jeb Hensarling, chairman of the House Financial Services Committee.
"I would say that it's wide open," House Republican Phil Gingrey told AFP.
House leadership met mid-day Wednesday in the Capitol to plot a path forward.
Three Republican sources told the Washington Post that Cantor will leave his leadership post by July 31.
Cantor lost his Virginia district seat to a former political unknown, economics professor Dave Brat who was backed by the anti-tax, small government Tea Party movement.
Experts and Cantor's colleagues said the majority leader failed to address the issues of his constituents, focusing more on national party priorities and fundraising for other candidates.
The result was widely considered one of the biggest upsets in modern US congressional history.
"I think he's going to be gravely missed," congressman Mario Diaz-Balart, one of a group of lawmakers trying to hammer out immigration reform legislation, told reporters.
"Anybody who can claim that they can know how this is going to affect any major issue is not understanding what a big tsunami this is."