Graham told CNN that while the Texas senator is not his preferred candidate, he's "the best alternative to Donald Trump," and he said he will "help Ted in every way I can."
A draft of the invitation, obtained first by CNN, invites guests to "honor and support a great friend of Israel and the Jewish people," at a meet-and-greet event that will take place during the AIPAC policy conference in Washington next week.
Graham, who ended his bid for the Republican nomination last December, originally threw his support behind former Florida Gov. Jeb Bush and campaign for him in South Carolina.
Support for Cruz
is an about-face for the South Carolina senator, who compared nominating GOP front-runner Donald Trump or Cruz to being shot or poisoned
. He recently mocked Cruz's unpopularity
among his colleagues, saying earlier this month: "If you killed Ted Cruz on the floor of the Senate, and the trial was in the Senate, nobody would convict you."
"He's certainly not my preference, but he's a reliable Republican, conservative, which I've had many differences with," the South Carolina Republican said.
When asked about his dramatic change in stance toward Cruz, Graham admitted that his Senate colleague is "not well liked," but said, "I have doubts about Mr. Trump, I don't think he's a Republican, I don't think he's a conservative, I think his campaign's built on xenophobia, race-baiting and religious bigotry, I think he'd be a disaster for our party and as Senator Cruz would not be my first choice, I think he is a Republican conservative who I could support."
On specific issues, Graham said he believes Cruz would be a reliable partner for Israel, would build the Keystone XL pipeline extension, would repeal and replace Obamacare and would nominate a true conservative to be on the Supreme Court.
Still, Graham said he believes that the third remaining Republican candidate for president, Ohio Gov. John Kasich, would be "the most viable general election candidate," but that he does not see how Kasich can win the primary.
The move is also a sign that Cruz might be starting to gain traction with his colleagues in the Senate.
Cruz picked up his first Senate endorsement
from Utah Sen. Mike Lee last week.