The relationship between President Trump and Senator Mitch McConnell, the majority leader, has disintegrated to the point that they have not spoken to each other in weeks, and Mr. McConnell has privately expressed uncertainty that Mr. Trump will be able to salvage his administration after a series of summer crises.
What was once an uneasy governing alliance has curdled into a feud of mutual resentment and sometimes outright hostility, complicated by the position of Mr. McConnell’s wife, Elaine L. Chao, in Mr. Trump’s cabinet, according to more than a dozen people briefed on their imperiled partnership. Angry phone calls and private badmouthing have devolved into open conflict, with the president threatening to oppose Republican senators who cross him, and Mr. McConnell mobilizing to their defense.
Great to see that Dr. Kelli Ward is running against Flake Jeff Flake, who is WEAK on borders, crime and a non-factor in Senate. He's toxic!— Donald J. Trump (@realDonaldTrump) August 17, 2017
At a campaign rally in Phoenix on Tuesday, Mr. Trump alluded to Mr. Flake unfavorably, referring to him as “weak on borders” and “weak on crime” without mentioning him by name. He referred to Mr. McConnell only in passing, calling on him to abolish the Senate filibuster.
Senior Republican officials said before the rally that they would stand up for Mr. Flake against any attacks. A Republican “super PAC” aligned with Mr. McConnell released a web ad on Tuesday assailing Ms. Ward as a fringe-dwelling conspiracy theorist.
“When it comes to the Senate, there’s an Article 5 understanding: An attack against one is an attack against all,” said Senator Lindsey Graham, Republican of South Carolina, who has found himself in Mr. Trump’s sights many times, invoking the NATO alliance’s mutual defense doctrine.