Republican senator: 'I’m out’ if GOP becomes party of David Duke, Donald Trump

Sen. Ben Sasse (R-Neb.) on Tuesday vowed to give up on the GOP if Donald TrumpDonald TrumpJohnson takes advantage of FBI review: There is a third option in every state How Republicans can move past Trump’s politics of personal ambition Clinton camp calls for FBI to release full details of probe MORE wins the party’s presidential nomination.

“Let’s first recognize that the Republican Party is just a tool, as all political parties are,” he told hosts Joe Scarborough and Mika Brzezinski on MSNBC’s “Morning Joe."

“I signed up for the party of Abraham Lincoln, not the party of David Duke, Donald Trump,” Sasse continued, linking the white nationalist with Trump’s White House run.

“I hope it happens over the course of the next 30 to 60 days that the Republican Party again becomes the party of Abraham Lincoln, limited government and great human potential. I want to celebrate what’s great about America in the Republican Party, but if the Republican Party becomes the party of David Duke, Donald Trump, I’m out.”

Sasse then rejected the notion that Trump could evolve into a stronger conservative.

“I don’t that this guy has any more core principles than a Kardashian marriage,” he said. "Do any of you think Donald Trump has any core values? I don’t think it’s conceivable."

Sasse additionally slammed his own party for helping fuel Trump’s popularity with voters nationwide.

“The core principles of the Republican Party have not been clear,” he said. "Ultimately, Donald Trump has seized upon a vacuous, falling-apart organization.”

Sasse has repeatedly challenged Trump’s fitness for the presidency, most recently penning an open letter late last Sunday night rejecting the billionaire’s campaign.

Trump is currently under fire for his hesitancy to denounce support from Duke, a former grand wizard in the Ku Klux Klan.

Duke urged listeners on his radio show last week to vote for the real estate tycoon, arguing that picking either Marco RubioMarco RubioWhy should a good person ever want to run for office again? Senate GOP pounces on FBI's Clinton probe Rubio won’t say if Trump would keep US safe MORE or Ted CruzTed CruzTrump knocks Kasich for breaking pledge Democrats pounce on Cruz's Supreme Court comments Brent Budowsky: An epic battle for the future of Congress MORE instead denotes “treason to your heritage."