House Speaker Paul Ryan reaffirmed his support for Donald Trump Thursday in his first comments since the GOP presidential nominee declined to endorse the speaker in an upcoming Republican primary.

"He won the delegates. He won the thing fair and square. It's just that simple," Ryan said in an interview on the "Jerry Bader Show" on WTAQ radio in Green Bay, Wisconsin.

Ryan brushed off Trump's non-endorsement, adding: "The only endorsements I want are those of my own employers here in the First Congressional District, and that's really what my focus is."

Ryan faces a longshot conservative challenger, Paul Nehlen, next Tuesday. Trump shocked Republican leaders yet again this week when he refused to declare support for Ryan, instead stating that "I'm just not there yet." The phrase echoed Ryan's own words in May, when he demurred on Trump, saying "I'm not there right now," before eventually going on to support him.

Ryan has been highly critical of Trump's attacks on a bereaved couple whose son died in Iraq and who took the stage at the Democratic National Convention to criticize Trump.

On Thursday, Ryan again condemned Trump's remarks about the Khans as "beyond the pale" and acknowledged that at some point, Trump could go too far for Ryan to be able to continue to support him.

Ryan said he didn't want to get drawn into "hypotheticals" but said, "None of these things are ever blank checks. That goes with any situation in any kind of race."

He also criticized Trump's wildly undisciplined campaign in the days since the Republican convention.

"We just came out of our convention, and yeah, he's had a pretty strange run since the convention. You would think we'd ought to be focusing on Hillary Clinton and all of her deficiencies," Ryan said. "She is such a weak candidate that one would think we'd be on offense against Hillary Clinton, and it is distressing that that's not what we're talking about these days."

The speaker said it is his duty to speak up against Trump on issues like the Khan family or his criticism of an American-born judge of Mexican descent whom Trump had also attacked.

"I don't like doing this. I don't want to do this. But I will do this," Ryan said. "Because I feel I have to, in order to defend Republicans, and our principles, so that people don't make the mistake of thinking we think like that."