Sen. Lindsey Graham, R-South Carolina, is pushing the Republican party to rally behind Ted Cruz as the "primary alternative" to presidential front-runner Donald Trump, despite Graham's long and storied history of opposing his Senate colleague.

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

When asked how he expects to convince fellow Republicans to support Cruz, Graham -- who once joked that the choice between Trump or Cruz for president was a decision between getting "shot or poisoned" -- quipped: "If I can do it, anybody can do it."

Graham, who gave his support to Cruz last month in a surprise endorsement, made the case that Trump is not a "reliable Republican" because "he's given money to every liberal Democrat into the world." The former Republican presidential candidate also slammed Trump's foreign policy proposals, calling them "jibberish" and observing that they have already made diplomatic efforts in the Middle East significantly more tense.

Pressed on why Ohio Gov. John Kasich would not make a better alternative, the South Carolina senator acknowledged that Kasich was "probably more electable" but that Cruz has run a better primary campaign.

"[Cruz] has become the primary alternative to Trump," Graham noted. "He represents the outside movement in the party. When you add up the votes, 65 percent of Republicans are wanting someone outside the system so Ted is in it but he's also an outsider."

Of the possibility that Republicans would face a contested convention in Cleveland in July, Graham predicted that the chances were "four-to-one it's going to happen."

Still, he cautioned against those members of the GOP who have suggested "parachuting" in another nominee at the last minute, shutting down that idea (and the possibility of a presidential bid by House Speaker Paul Ryan) as a detrimental one for the party.

"I'm trying to get us the most viable nominee for 2016 that could win without destroying the party," Graham said. "The bottom line is millions of people have gone to the polls and cast their ballot, and if 2000 of us take that choice away, then I think we destroy the Republican party forever."