If President Donald Trump ultimately caves on his demand for border wall funding amid a partial government shutdown, then that “probably” will mark “the end of his presidency,” Sen. Lindsey Graham (R-S.C.) warned on Wednesday night on Fox News’ “Hannity.”

Trump campaigned heavily on his now-iconic pledge to build a security wall along the U.S.-Mexico border to prevent illegal immigration.

Although Republicans held majorities in both the House and the Senate for the first two years of Trump’s presidency, lawmakers could not reach an agreement on funding the border wall — and punted on the issue.

Now that Democrats have retaken the House majority, the $5 billion in border wall funding that Trump is demanding becomes even more difficult to attain.

Although Trump and GOP lawmakers showed their willingness to lower the $5 billion request in a compromise, newly minted House Speaker Nancy Pelosi (D-Calif.) and Senate Minority Leader Chuck Schumer (D-N.Y.) still are refusing to budge on providing a cent of border wall funding.

“I don’t know how this movie is going to end, but we are not giving up until we get the money,” Graham told Fox News host Sean Hannity. “[Trump] is not going to sign a bill that doesn’t have money for the wall.”

“The president is going to challenge the Democrats to compromise. If they continue to say no, they are going to pay a price with the American people,” Graham said.

Claiming that “most Americans” want “to secure our border” and still “be reasonable” when dealing with illegal immigrants brought to the U.S. as children, Graham said Trump must remain firm in seeking wall funding while compromising where he can.

“If he gives in now, that’s the end of 2019 in terms of him being an effective president. That’s probably the end of his presidency,” Graham warned.

“Donald Trump has made a promise to the American people. He’s going to secure our border. Every Democrat in the past has been for border funding. Now they are changing their mind,” Graham added.

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When Hannity asked him if there were other ways Trump could bypass Congress to provide border wall funding, Graham said the president could “move some money around” from government agencies, such as the Department of Homeland Security (DHS).

“But he’ll get sued. There’ll be lawsuits in California to stop any effort to have other agencies fund the border,” Graham lamented. “But why should this president have to play that game? Why should Donald Trump have to do that when Democratic presidents and Republican presidents in the past were able to get money to secure the border from Democrats?”

“That’s the end of us if we give up on this issue as Republicans,” Graham added.

He isn’t the only Republican predicting a 2020 re-election failure for Trump if he caves on border wall funding.

Related: Democrats Kept Interrupting Border Wall Briefing Because It Violated Their ‘Talking Points’

Conservative commentator Ann Coulter claimed on Wednesday on “The Mark Simone Show” on New York’s WOR-AM radio station that Trump will “fold in the end.”

“Trump will just have been a joke presidency who scammed the American people, amused the populists for a while, but he’ll have no legacy whatsoever,” Coulter said. “If he doesn’t build the wall, the next president will be a Democrat.”

“I think the people of this country think I am right. Again, I could have had a lot easier presidency by doing nothing, but I’m here. I want to do it right,” Trump said.

Pelosi told Savannah Guthrie of NBC News during an interview that aired Thursday on the “Today” show that Democrats will give “nothing for the wall.”

But Trump said Wednesday during a Cabinet meeting that the government will remain partially shut down over border wall funding for “as long as it takes.”

“I mean, look, I’m prepared. I think the people of this country think I am right. Again, I could have had a lot easier presidency by doing nothing, but I’m here. I want to do it right,” Trump said.

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