Mr. Cruz and White House officials now speak with mutual warmth, recounting their work together on tax legislation, disaster relief for Texas after Hurricane Harvey and the pardon granted Dinesh D’Souza, the conservative author and filmmaker.

“Surprisingly good,” Mr. Cruz said of their relationship.

Last month, Mr. Trump endorsed Mr. Cruz at the National Rifle Association convention in Dallas.

“You’re looking at allies,” said Kellyanne Conway, the White House counselor, who herself supported Mr. Cruz for president before joining Mr. Trump.

In interviews with Republican activists and voters, few seemed to hold a grudge against Mr. Cruz for his 2016 speech.