The escalating clash between Paul Ryan and Donald Trump is prompting warnings of retaliation against the speaker from rank-and-file House Republicans.
That means the Wisconsin Republican could face a rebellion like the one that drove former Speaker John Boehner into retirement, testing Ryan's hold on his own job.
Ryan told GOP lawmakers this week that he won't defend his party's presidential candidate or campaign with him and urged them to do whatever it takes to win re-election.
His statement followed the release of a 2005 video showing Trump making vulgar comments about how he sexually pursued women.
Republican congressman Jim Bridenstine of Oklahoma tweeted Wednesday, "Given the stakes of this election, if Paul Ryan isn't for Trump, then I'm not for Paul Ryan."