Mr. McConnell made clear his unhappiness to the White House after a “super PAC” aligned with Mr. Trump started an ad campaign against Senator Dean Heller, Republican of Nevada, when he said last week that he opposed the health care bill.
The majority leader called the White House chief of staff, Reince Priebus, to complain that the attacks were “beyond stupid,” according to two Republicans with knowledge of the tense exchange on Saturday.
Mr. McConnell, who has been toiling for weeks, mostly in private, to put together a measure that would satisfy hard-liners and moderates, told Mr. Priebus in his call that the assault by the group, America First, not only jeopardized the bill’s prospects but also imperiled Mr. Heller’s already difficult path to re-election.
America First was founded by a group of Mr. Trump’s loyalists — many of them with deep connections to Mr. Pence, including Nick Ayers, a Republican consultant who is regarded as the vice president’s top political adviser. The PAC compared Mr. Heller to Representative Nancy Pelosi, the House Democratic leader, and vowed a seven-figure advertising campaign against him.
Josh Holmes, Mr. McConnell’s former chief of staff, said, “That the White House is asking people to take a tough vote and then running ads against members while we’re still in negotiations is so dumb it’s amazing we even have to have the conversation.”