"I will tell you this, if the Republican Party comes into that convention and jimmies with the rules and takes away the will of the people, the will of the Republicans and the Democrats and independents who voted for Mr. Trump, I will take off my credentials, I will leave the floor of that convention, and I will leave the Republican Party forever," Sam Clovis, a national co-chair for Trump's campaign, said in an interview with Alisyn Camerota on CNN's "New Day" on Friday.
Clovis' comments come just days after Trump told CNN that his supporters would "riot"
if the real estate mogul was denied the nomination in a floor fight.
Trump needs 1,237 delegates to clinch the party's nomination. If he falls short of that goal, he could face a convention floor fight this summer.
Clovis also discussed a meeting in Washington on Thursday
of a group of conservative leaders, led by Erick Erickson, a blogger and radio host, and other conservative donors and influencers, who are committed to stopping Trump's candidacy.
"If it was not so ridiculous, it would be laughable what's going on inside," he said. "I would consider this. We have people who are elitists, who are part of the ruling class of this country, or pretenders to that throne, who are openly and willingly going out here and telling the American people who have voted for Donald Trump that they're stupid and they don't know any better."
"I want to tell you, if that's the path they want to go down, there will be consequences for that kind of thing."
Pressed to elaborate on the threat, Clovis said, "I think the consequences are going to be that what they think the Republican Party is is not going to be what the Republican Party is after the convention."
And Clovis was blunt about the options remaining for the anti-Trump holdouts: "They will have to figure out whether they want to get on the train, or they're going to end up under the train. It's up to them."
Appearing later Friday on CNN's "OutFront" with Erin Burnett, Clovis said "someone who would know" told him a contested convention is "not going to happen."
Clovis also called Mitt Romney -- who endorsed Trump foe Ted Cruz on Friday
-- and others who want to thwart Trump at the convention "a bunch of sore losers," adding that the campaign will be ready for such a contingency if it happens.