Sen. Lindsey Graham said on "Hannity" that if Republicans don't support President Trump's border security plan, it would mean the end of his presidency.

His remarks come after Trump addressed the nation from the Oval Office about the situation at the southern border.

Graham -- speaking to his fellow Republicans -- said that right now is the best chance Trump has to get border wall funding.

"If [Republicans] undercut the president, that's the end of his presidency and the end of our party," he said. "And we deserve to be punished if we give in now."

'A Choice Between Right & Wrong': Trump Addresses Nation on Border, Dems Say He's 'Chosen Fear'

Graham (R-S.C.) called the president's national address "compelling" and his words "completely true."

Trump described the situation at the southern border as a "humanitarian and security crisis," and that "uncontrolled" illegal migration is hurting American citizens.

"I'm flabbergasted to hear from my Democratic colleagues who voted for billions of dollars in border security money that this is manufactured," Graham added.

He said that Trump's administration will never get a border security deal completed until "radicals are set to the side."

"If Democrats want a fight, they're going to get one," he said. "If they want to solve the problem, we'll do that too."

Watch more of the discussion with Sean Hannity above.

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