Republican vice presidential candidate Mike Pence played fireman on Wednesday by announcing he was endorsing House Speaker Paul Ryan in his primary bid with the support of Donald Trump, just a day after Trump declined to back the speaker's re-election.

"I talked to Donald Trump this morning about my support for Paul Ryan and our long-term friendship and he strongly encouraged me to endorse Paul Ryan in next Tuesday's primary and I'm pleased to do it," Pence, the governor of Indiana, said on Fox News.

Trump and the Republican National Convention speakers devoted themselves to presenting an image of party unity, but then the GOP nominee tweeted a compliment at Ryan's primary opponent, Paul Nehlen, and then publicly refused to endorse the speaker. The episode has frustrated Republicans, especially party leaders who have tried to enforce GOP unity in the wake of Trump's presidential primary victory.

"These two men are going to do great things to restore this country at home and abroad," Pence said. "In politics, it takes time to get relationships going ... I think we need Paul Ryan in the Congress of the United States to rebuild our military, to strengthen our economy and to ensure that we have the kind of leadership in this country that will make America great again."

Trump was less complimentary. "I like Paul, but these are horrible times for our country," he told the Washington Post. "We need very strong leadership. We need very, very strong leadership. And I'm just not quite there yet. I'm not quite there yet."

Trump's allies are reportedly planning to stage an "intervention" in an attempt to get his campaign on track. "It's like watching a team go out on the field, throw an interception on the first play and go back off the field again," former House Speaker Newt Gingrich, who was once a finalist to be Trump's running mate, said on Fox Wednesday morning.

Pence dodged a question about such an intervention. "You're always going to hear these kind of inside-the-baseball discussions," he said. "I've never heard anything of that kind."