"Can Cruz win?" the Texas senator said here at The Venetian hotel before the Republican Jewish Coalition, warning that he would "get a little wonky" before hundreds of leaders. "The best policy positions in the world don't mean squat if you lose."
Cruz, acknowledging that he likely disagrees with those in the crowd on immigration and social issues such as gay marriage, noted correctly that he was not the first choice of many Republicans in the room.
But he stressed to Jewish leaders here that he was both their best chance to maintain GOP control of Congress -- key to conservative foreign policy hands -- and the best second choice they have in the race, raising the specter of a blowout should Trump lead the GOP ticket.
"If the top of the ticket is blown out of the water by 10 points, we're losing the Senate. And there's not a thing that can be done to stop it," Cruz said, saying a Trump candidacy would lead to a "bloodbath of Walter Mondale proportions."
Cruz, saying he and the "sophisticated political audience" have "enormous agreement" on policy, instead aimed to convince the Republican Jewish Coalition that a vote for him would not be wasted, outlining in detailed nuts-and-bolts that he has a path to beat Trump and then the Democratic nominee in November.
Many in this audience of prominent Republican donors feel that while Cruz is in sync with them on protecting Israel, he is too brash in tone and conservative in policy to win. On Saturday evening, Cruz tackled that perception head-on.
And he suggested that the favor Trump had curried with the pro-Israel community thanks to a speech at another Zionist summit, AIPAC, was only so successful because he "read (a) promise off teleprompters."
But Cruz's most pressing task was to pitch politics, not policy.
Cruz on Saturday rested his case more than ever before on an open Republican National Convention, saying "delegate math" was on his side, as he professed that he had a legitimate path to the White House.
Cruz said his recent under-the-radar victories in a battery of state delegate battles made it "almost impossible" for Trump to win the 1,237 delegates needed to avoid a contested convention in Cleveland. And Cruz confidently predicted that he was almost certain to defeat Trump there.
"I believe the first ballot will be the highest vote total Donald Trump receives. And on a subsequent ballot, we're gonna win the nomination and earn the majority," Cruz said. "We have to achieve that unity -- and we've got just over 100 days to do it."
And in a general election, when some fear Cruz may be too conservative to win?
He pledged to not be a "hectoring scold" on issues such as abortion. He boasted that he could put states like Pennsylvania in play, rattling off general election polls in a battery of states. And he predicted that he would be more successful at uniting the Republican Party after a fractious primary battle than Hillary Clinton would be at coalescing a Democratic Party split between her and Bernie Sanders.
Cruz, hyper aware of his audience, knew from the outset that he had people to convince. And soon after wishing them a "Good Shabbos," the Texas senator signaled that he believed they were slowly being won over.
"This is a room full of people who are good friends," he said, "and who are becoming good friends."