WASHINGTON — A former Trump campaign aide spent much of Monday promising to defy a subpoena from special counsel Robert Mueller, even throwing down the challenge to “arrest me,” then backed off his defiance by saying he would probably cooperate in the end.

In an interview with The Associated Press, Sam Nunberg said he was angry over Mueller’s request to have him appear in front of a grand jury and turn over thousands of emails and other communications with other ex-officials, among them his mentor Roger Stone. But he predicted that, in the end, he’d find a way to comply.

“I’m going to end up cooperating with them,” he said.

It was a reversal from his tone throughout the day, when he lashed out at Trump and his campaign and threatened to defy Mueller in a series of interviews.

“Why do I have to do it?” Nunberg told CNN of the subpoena. “I’m not cooperating,” he said later as he challenged officials to charge him.

In the earlier interviews, Nunberg said he thought Mueller may already have incriminating evidence on Trump directly, although he would not say what that evidence might be.

“I think he may have done something during the election,” Nunberg told MSNBC of the president, “but I don’t know that for sure.” He later told CNN that Mueller “thinks Trump is the Manchurian candidate.” The reference is drawn from a Cold War novel and film in which a “Manchurian candidate” is an American brainwashed or otherwise compromised to work on behalf of an adversarial government.

Shortly after Nunberg lobbed the first allegation, White House press secretary Sarah Huckabee Sanders rebuffed him during the White House press briefing.

“I definitely think he doesn’t know that for sure because he’s incorrect. As we’ve said many times before, there was no collusion with the Trump campaign,” Sanders said. “He hasn’t worked at the White House, so I certainly can’t speak to him or the lack of knowledge that he clearly has.”

Nunberg also said he thinks former Trump foreign policy adviser Carter Page, a key figure in the Russia investigation, worked with the Kremlin. “I believe that Carter Page was colluding with the Russians,” Nunberg said on CNN. “That Carter Page is a weird dude.”

Page called Nunberg’s accusations “laughable” in a comment to The Associated Press.

The Justice Department and FBI obtained a secret warrant in October 2016 to monitor Page’s communications. His activities during the presidential campaign that raised concerns included a July 2016 trip to Moscow.

In the interviews, Nunberg said he believes the president probably knew about the June 2016 Trump Tower meeting between his eldest son, top campaign staff and a team of Russians, which Trump has denied. And he blamed Trump for the investigation into Russia meddling, telling MSNBC that he was “responsible for this investigation … because he was so stupid.”