Ted Cruz is pleading with his Republican presidential rivals to “prayerfully” consider getting out of the race and support his bid in order to stop front-runner Donald Trump from clinching the nomination. He had a strong case to make after winning six states through Tuesday afternoon, coming within a few points of Trump in several others, and gaining ground in national polls.

But he’s getting no support from U.S. Senate colleagues, even after a seventh victory on Tuesday night in Idaho put him fewer than 100 delegates behind Trump and more than 200 delegates ahead of Marco Rubio, who has won just two contests out of 24 so far.

“It's surely significant that not a single Republican senator has endorsed him, including very conservative senators,” Senator Susan Collins of Maine told reporters prior to Tuesday’s results.

When Alabama Senator Richard Shelby was asked, he offered a curt reply: “I'm going to lunch.”

Despite his lackluster performance so far, the allies of Senator Rubio of Florida are sticking with him in the hope that he wins the 99-delegate Florida primary on March 15. His supporters saw few hopes of a revival in a quartet of contests on Tuesday evening. He was the only Republican candidate expected to pick up zero delegates from any of the day’s races.

“Hogwash,” South Carolina Senator Tim Scott said, prior to Tuesday’s results, of rumors that Rubio's campaign may suspend before Florida. Utah’s Orrin Hatch, North Carolina’s Thom Tillis, Oklahoma’s James Inhofe, Arizona’s Jeff Flake and Kansas’ Pat Roberts said they remain committed to Rubio.

“I don’t think he needs to turn it around, he just needs to keep going forward,” Scott said of Rubio. “I think he’s going to do really well for the rest of the week and have a great day in Florida next week.”

Ohio Governor John Kasich's campaign is holding firm until his home-state primary on March 15. On Tuesday, Ohio Senator Rob Portman reaffirmed his support for Kasich. “I'm fine with Ted, but I'm very excited about John Kasich,” Portman said. “I think we're going to win Ohio.”

‘Everybody Knows Why’

Cruz is the only Republican candidate without any Senate endorsements. In interviews Tuesday with 18 senators, there was scant indication they're heeding Cruz’s call to unite behind his campaign. When asked why the Texan lacks Senate support, their answers ranged from awkward chuckles and long silences to no-comments and briskly walking into a senators-only elevator to evade the question.

“I think it’s a whole list of things,” said Indiana Senator Dan Coats, telling Bloomberg Politics that “everybody knows why” Cruz doesn’t have any Senate supporters.

Republican senators' antipathy for Cruz is the worst-kept secret in Washington, owing to bad blood as a result of Cruz’s scorched-earth tactics, such as forcing an unsuccessful government shutdown in 2013 and calling Senate Majority Leader Mitch McConnell a liar on the floor of the chamber last year. The widespread perception remains that Cruz is willing to throw his colleagues under the bus to boost his own ambitions.

“His tenure in the Senate so far, for the most part, has been being kind of a disruptor,” said Senator John Thune of South Dakota, the third-ranking Republican in the chamber. “I think very early on, he had decided that he was going to make a national run and that’s probably kinda where he’s put his efforts and energies.”

Many aren’t sure Cruz would be preferable to Trump, either. When asked which of the two he’d rather see as the nominee, Flake let out a nervous laugh and said he's still supporting Rubio.

Even fellow Texan and Senate Majority Whip John Cornyn pleaded the fifth when asked about Cruz’s lack of support from colleagues. “You know, I think I’m going to invoke the McConnell rule and not talk about the presidential primary,” Cornyn said.

No Regrets for Shutdown

The government shutdown of 2013, a quixotic and failed effort to defund Obamacare, was led by Cruz and a small group of House Republicans who met regularly at a modest Tex-Mex restaurant a short walk from the Capitol building called Tortilla Coast. When the government re-opened 16 days into the shutdown, many Republicans were slammed by the base as sellouts. Since then, Cruz’s relations with colleagues have only gotten worse.

“It clearly was a tough time around here for the Senate,” Thune said. “I think what was frustrating about that was there were expectations created that somehow we could win. And I think all along it was pretty clear we weren’t going to succeed there. So it was frustrating for a lot of us, having to go through that process. But hopefully lessons have been learned by everybody.”

Cruz has never expressed regret for his effort, which turned him into a hero with the conservative base, and which he has since tried to repeat in pursuit of other goals like blocking President Barack Obama’s immigration policies. On the campaign trail, his battle against GOP leaders is a centerpiece of his pitch to voters—in his telling, he’s the only candidate unafraid to take on his own party.

“The only thing he’s said he'd have done differently is try to lay more groundwork in selling the strategy to the media, so when we were undercut by Senate Republicans, people would have a better understanding of what we were trying to accomplish,” said Amanda Carpenter, a former senior aide for Cruz during the shutdown debate. “We were out-gunned in many respects. So not knowing how outgunned we’d be on the communications side, we should’ve done more work on the front end to try to box people like Mitch McConnell and [former House Speaker] John Boehner into our strategy.”

North Carolina Senator Richard Burr, who in 2013 called the shutdown “the dumbest idea I've ever heard,” held his tongue Tuesday when asked about Cruz. “I’m not getting into the presidential election,” he said. “Good try.”

‘Death by Being Shot or Poisoning’

Senator Dan Sullivan of Alaska, a state won by Cruz last week, had nothing but nice things to say about him, though his endorsement remains up for grabs.

“I actually have a lot of respect for Senator Cruz,” he said, adding that he doesn't believe “media stories” about Cruz not having friends in the Senate. “That's not been my experience. I think he’s a strong advocate for Texas.”

A new ABC/Washington Post national poll released Tuesday found Cruz in second place, 9 points behind Trump, although more Republicans (65 percent) said they'd be “satisfied” with Cruz than with any other candidate. A second poll out Tuesday, by NBC News and the Wall Street Journal, found Cruz just three points behind Trump. Rubio came third place in the ABC poll and fourth place in the NBC poll.

In January, Senator Lindsey Graham of South Carolina compared a Trump-or-Cruz choice as a choice between “death by being shot or poisoning.” Graham has spent months sounding the alarm that a Trump nomination would accelerate a demographic death spiral for the party by making it toxic with the growing bloc of Hispanic voters.

“Ted Cruz is not my preferential choice, but I believe he's a Republican conservative and Trump’s not,” Graham said. “Bottom line is I think he’s more electable than Trump. I don’t know how much that is.”

“I think he's the most viable alternative as of right now to Trump. He’s shown some ability to beat Trump,” he said.

—With assistance from Steven T. Dennis in Washington.

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