South Carolina Sen. Lindsey Graham said he believes the Republican Party will end if it nominates either Donald Trump or House Speaker Paul Ryan.

Graham, a reluctant supporter of Texas Sen. Ted Cruz's presidential bid, told CBS that Republicans need to unite behind Cruz to save the party.

"Let me say this, my Republican friends: If you parachute somebody in just on electability — Paul Ryan's a wonderful guy, doesn't want to be put in this position. I'm trying to get us the most viable nominee for 2016 that could win without destroying the party," Graham said. "I think Trump destroys the party. And if you parachute somebody in, and try to ignore millions of votes, you're going to destroy this party. So we're right back to Ted."

Asked how Republicans who dislike Cruz could support the Texas senator's campaign, Graham said, "If I can do it, anybody can do it."

"Ted Cruz is a Republican, he's smart as hell, he's run a very effective campaign and we have a lot in common. But we also have some real differences," Graham said. "He is a real Republican from the more ideological spectrum than I am, but he would not destroy our party. Trump would."

Graham urged Republican voters to hang with the party even if they do not support the man at the top of the ticket.

"We're in the process of six-putting in the Republican primary, just bear with us," he said.