AUSTIN — If Donald Trump scoops up a big share of Texas delegates March 1, it will do more than boost the bombastic billionaire businessman — it will call into question the path forward for home-state U.S. Sen. Ted Cruz.

And if Trump defies expectations to win the Lone Star State outright, that could be the end for Cruz’s campaign.

“If (Cruz) can’t win Texas, where does he win?” asked Trinity University political scientist David Crockett.

With Texas considered not only a must-win but a must-win-big state for Cruz in the race for the GOP presidential nomination, Republicans concerned about Trump’s rise are watching closely.

Trump “looks on pace to get second” in the Texas primary, but he has momentum, said Republican consultant Brendan Steinhauser.

“He’s got a lot of support. He could do well in Texas,” Steinhauser said. “Personally, I’m worried about it. I think a lot of Republicans are.

“I think Donald Trump would be terrible for the Republican brand as our nominee. And I don’t think that he beats Hillary Clinton,” said Steinhauser, who also said Trump’s “negatives and his kind of insulting way” will play badly in the general election.

Cruz has natural advantages in Texas, where he beat then-Lt. Gov. David Dewhurst to win the U.S. Senate seat in 2012 with strong support from tea party activists. He has traveled the state extensively, starting with that race, and has a strong organization that his campaign has said includes 27,000 volunteers.

Texas also is important for U.S. Sen. Marco Rubio of Florida, who in the wake of former Florida Gov. Jeb Bush’s decision to suspend his campaign is the leading establishment-oriented candidate remaining in the race.

“I still think Rubio is kind of a close second or third,” said Steinhauser, who worked for the Senate campaigns of Cruz and Rubio when he was with the limited-government group FreedomWorks. “It looks very much like this is a three-way race all the way to the convention.”

Former Cruz campaign spokesman Rick Tyler — before Cruz asked him to resign Monday over a social media post about Rubio — said on CNN Saturday that “I think we have to win Texas.”

Then in a Fox interview Monday, asked if he would predict a Texas win, Tyler said, “I’m not going to predict anything, but we hope to do well there, absolutely.”

Trump spokeswoman Hope Hicks sounded a positive note about his prospects, saying he “has had tremendous support in Texas since announcing his candidacy” and “has great respect for the people of Texas.”

Crockett counted Trump’s primary victories in New Hampshire and South Carolina as carrying more weight than Cruz’s win in the Iowa caucuses.

“Caucuses are weird animals,” said Crockett, pointing out that they require energy and a large time commitment from voters. “Most of the contests are primaries, and Trump has won the first two, in both cases by double digits. That’s a recipe for victory in the end if that dynamic doesn’t change.”

Rubio spokesman Micah Johnson, whose candidate edged out Cruz in South Carolina, said, “Marco left South Carolina with a ton more momentum and support than he had when he got there. … As the field winnows, Marco will continue to rise, and we believe we are very well-positioned heading into March.”

Rice University political scientist Mark Jones flatly predicted Trump would not win in Texas.

“That isn’t going to happen. But he could do well in Texas, and that would be very bad for Ted Cruz,” Jones said. “Cruz doesn’t just need to win in Texas. He needs to win big in Texas.”

If somehow Cruz failed to come in first, Jones said, “then he does probably need to consider dropping out. What is your route to victory if you can’t win Texas?”

On the other hand, Jones said, if Cruz gets more than 50 percent of the vote statewide, “That would be a resounding success and a real sort of nitro-boost for his candidacy.”

Cruz needs to do well in Texas, not just because of the image problem he would otherwise suffer but because he needs to make strides toward collecting the 1,237 delegates required for the nomination, Jones said.

Texas’ 155 delegates, the largest number at stake in the multistate Super Tuesday primary, are awarded in a “graduated proportional” method. Most are allocated through the 36 congressional districts, with three per district. The remaining 47 are allocated based on the statewide vote.

A candidate topping 50 percent of the vote gets all the delegates in a geographic region, whether in a congressional district or statewide. Short of 50 percent, the process favors those who get at least 20 percent of the vote.

Political scientist Walter Wilson of the University of Texas at San Antonio said Cruz “really is unproven as a GOP standard bearer in the state,” having beaten Dewhurst “in a very-low-turnout runoff” in the GOP primary in 2012 and then besting a “severely underfunded and outmatched Democratic opponent” that year.

As for Trump, he said, “it will become clearer if Trump has reached a ceiling of support” as the race narrows.

“Put those factors together, and you come up with a pretty competitive race, with no clear advantage. To generate momentum, Cruz will have to outperform expectations by scoring a decisive victory in Texas,” Wilson said. “If the race is close, it will solidify Trump and perhaps elevate Rubio as the major alternative. Regardless, Cruz’s pathway to the nomination appears to be narrowing.”

The most recent Texas polling posted on Real Clear Politics shows Cruz leading Trump in Texas, but the survey results are from last month, before the narrative changed with Trump’s South Carolina win.

On the positive side for Cruz, said former state GOP chairman Steve Munisteri, Texans started voting before the South Carolina primary. Texans could apply for mail-in ballots starting in January, and polling places opened Feb. 16.

“If they (the Cruz campaign) saw any weakness in Texas at all, I’m assuming they would redeploy resources here. He cannot afford to lose Texas,” said Munisteri, who was senior adviser to U.S. Sen. Rand Paul’s campaign before the Kentuckian suspended his effort. “If he loses Texas, his whole argument goes out the window that he could be the candidate for the conservative wing.”

But the difficulty of getting 50 percent of the vote in a field with multiple candidates will give a talking point to Trump, Munisteri said.

“My guess is he doesn’t get 50 percent statewide,” Munisteri said, “which then allows Trump to say over half of Texans didn’t like him.”

pfikac@express-news.net