Donald Trump declined to endorse House Speaker Paul Ryan and two Republican senators who face tough re-election bids, claiming on Tuesday that he's "not quite there yet."

"I like Paul, but these are horrible times for our country. 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," the Republican presidential nominee said of endorsing Paul Ryan during an interview with the Washington Post.

Ryan, who ultimately decided to back his party's nominee, gave a similar answer in May when he was first asked about endorsing Trump. "To be perfectly candid, I'm not ready to do that right now," he had told CNN.

The Wisconsin Republican is being challenged by local businessman Paul Nehlen in his state's congressional primary, which is scheduled to take place next Tuesday. Trump posted a tweet on Monday in which he thanked Nehlen for his "kinds words" of support after the candidate found himself embroiled in controversy for attacking Khizr and Ghazala Khan, two Gold Star parents who've been critical of him.

"I'm giving very serious consideration to that whole situation, to Ryan, to Paul," Trump told the Post.

Trump also said that he's had a "difficult time" deciding whether to endorse John McCain because he believes the Arizona senator "should have done a much better job for the vets." McCain slammed Trump in a statement on Monday, claiming his criticism of the Khans "do not represent the view of our Republican Party, its officers, or candidates."

"He has not done a good job for the vets and I've always felt that he should have done a much better job for the vets," Trump said of McCain. "So I've always had a difficult time with John for that reason, because our vets are not being treated properly."

New Hampshire Sen. Kelly Ayotte, who is being challenged by her state's Democratic governor, is also unlikely to receive Trump's endorsement, the candidate hinted.

"I don't know Kelly Ayotte. I know she's given me no support — zero support — and yet I'm leading her in the polls. I'm doing very well in New Hampshire. We need loyal people in this country. We need fighters in this country ... We need fighters in this country, but Kelly Ayotte has given me zero support, and I'm doing great in New Hampshire," he said.

Ryan's campaign issued a statement denying ever seeking Trump's endorsement.

"Neither Speaker Ryan nor anyone on this team has ever asked for Donald Trump's endorsement," the statement reads. "And we are confident in a victory next week regardless."

Ayotte issued a sharp rebuke of Trump's criticism.

"I call it like I see it, and I'm always going to stand up for our military families and what's best for the people of New Hampshire," she said in a statment.

Ryan, Ayotte and McCain have all vowed in one way or another to support Trump as their party's presidential nominee.