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Donald Trump on Friday brushed aside comments from House Speaker Paul Ryan that representatives should follow their conscience on the controversial candidate, and said if Republicans don’t have anything nice to say they shouldn’t say anything at all.

"He’s got to do what he’s got to do," Trump said of Ryan’s comments earlier in the day that he wouldn’t instruct Republican House members to vote for Trump.

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Trump’s candidacy has been problematic for some establishment Republicans.

Ryan, the top Republican in Washington, said he wouldn’t tell House members to vote against their conscience, and said of the current environment, "this is a very strange situation. This is a very unique nominee."

Trump, in a brief phone interview with NBC News, dismissed concerns over party unity.

"If they can't stay positive they should probably not say anything at all because I’m going to win the race," Trump said.

Trump’s candidacy has caused fears among some that Republicans in down-ballot races across the country could suffer with Trump at the top of the ticket. Former President George W. Bush is helping vulnerable senators out of concern about Trump's message and impact.

"I think he's perturbed by the fact that his brother did very poorly against me," Trump said of Bush, referring to Jeb Bush’s failed presidential campaign. "He can't be thrilled by that."

Trump wouldn’t elaborate on what he believes to be the former president’s motivation, saying: "I think he's doing it for whatever reason. I love that he's helping other Republican senators."

Trump, who has repeatedly made claims that he was self-funding his campaign in the primary and is immune from what he characterizes as the influence peddling of big-money politics, just completed a fundraising swing through Texas that sources said netted the candidate $8 million in all.

Trump defended the fundraising and claimed he doesn’t make personal appeals for cash. "I don't say that," Trump said, "They come to me."