Republican presidential contender Sen. Ted Cruz (Texas) received the less-than-glowing endorsement of South Carolina Sen. Lindsey Graham Thursday, a sign the Republican establishment may be rallying together to stop GOP front-runner Donald Trump.

But, according to the billionaire businessman, a Graham endorsement is not one his presidential counterpart should want. In fact, Trump tweeted “Lyin’ Ted,” telling him that the senator’s endorsement is a bad-luck omen for his campaign.

“Lyin’ Ted Cruz lost all five races on Tuesday-and he was just given the jinx — a Lindsey Graham endorsement,” Trump tweeted Friday afternoon. “Also backed Jeb. Lindsey got 0!”

After ending a presidential campaign in December of last year — a campaign that never seemed to gain much traction — Graham threw his support behind one-time Republican presidential candidate Jeb Bush. The former governor of Florida ended his own run after an unimpressive showing in the South Carolina primary last month.

Trump currently leads the delegate count with 678, followed by Cruz with 413 and Ohio Gov. John Kasich with 143. The Republican front-runner is hoping to unite the party around his candidacy, but has received pushback from establishment GOP leaders and others who do not believe he is a committed conservative.

Graham, hoping to slow Trump’s momentum, will host a fundraising event this Monday for Cruz — a man of whom he once said, ”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,” Graham said of Cruz.

Follow the author of this story on Twitter: