Houston (CNN) Of all the states, Texas was the one Ted Cruz was not supposed to have to worry about.

As reviled as he may be back in Washington, Cruz has been adored here at tea party rallies and Republican conventions ever since he first upset the political establishment with a shocking come-from-behind victory in 2012. In his home state, Cruz often comes across as a rock star, a leader so admired by the grassroots that his endorsement in legislative primaries is the closest thing to a gold standard in state politics.

But thanks to Donald Trump and Marco Rubio , Cruz's shot at becoming President may end in Texas.

Cruz, despite his appeal as a native son ideologically in sync with a ruby red Republican base, could very well lose the Texas primary next week, a setback that would strike at the core of Cruz's southern political strategy.

Both Trump and Rubio are squeezing Cruz in the Lone Star State, cutting into his lead by blanketing the airwaves and working side by side to engineer an upset. Trump continues to hit Cruz with claims the senator is a "liar," and Rubio wants to show he can win establishment and anti-Trump votes, which means taking from Cruz.

Cruz aides remain optimistic that he can still compete elsewhere on Super Tuesday , but they have nevertheless sent stakes for his performance back on his home turf to new heights.

"This is make or break for Cruz. He has to win -- no close second is good enough," said Bill Miller, an unaligned, senior Republican lobbyist here. "Unquestionably he's favored -- and it has been in the bag -- but the bag has a weak bottom."

Most political observers still give Cruz the slight upper hand and expect him to claim the plurality of the state's 155 delegates, which his team believes can put him close to even in the delegate race after March 1.

And Cruz certainly is not taking Texas for granted -- working the state's political machinery since the moment he announced and on Wednesday rolling out his highest-ranking endorsement yet anywhere in the country, Texas Gov. Greg Abbott.

The question, however, is whether of any of that will be able to stop the freight train of momentum that is Trump, who is planning a huge rally in Fort Worth on Friday morning.

"Most people are just listening to the message, and they're not necessarily going to have loyalty toward Cruz just because he's our current senator," said Wayne Richard, a Dallas-area activist supporting Trump. Richard acknowledged Cruz's strong field program, but was skeptical it would make much of a difference and that Texas could have a "devastating impact" on Cruz's White House hopes.

Recent polling has shown Cruz with a solid, but not insurmountable lead over Trump. A Monmouth University survey released Thursday gave Cruz a particularly wide margin, putting him 15 points above Trump. And Cruz's vaunted ground game numbers 27,000 volunteers, which observers say gives Cruz even more of an edge.

Cruz is doing virtually nothing to tamp down expectations. On Tuesday, he called March 1 "the single most important day in this presidential election."

Rubio makes his play

But it's not just Trump that poses a threat: Cruz is also confronting an increasingly dangerous Rubio, whose campaign would like nothing more than to kneecap their arch-rival in his home state.

The Florida senator's super PAC has made its largest investment on Super Tuesday in Cruz's home state, sinking millions of dollars into territory it might not win with the hopes of embarrassing the candidate who really needs it.

Rubio also stands to benefit from the Bush bundler network, which is particularly deep in this town, migrating over into his camp.

"Rubio or bust," said Jacob Monty, a former Bush fundraiser here. "No one from Bush has gone anywhere but Rubio. Rubio is the only hope for rational Republicans who would like to win the general."

Monty, like other Latino Republican leaders in Houston, have also gravitated to Rubio. He was introduced at a rally in a hotel ballroom Wednesday afternoon by two of the country's most prominent Hispanic Republicans, and his crowd was more solidly Latino than most Cruz crowds.

"You're from Texas," Rubio told his supporters when someone interrupted him to shout something in Spanish. "You know what he said."

Rubio's team recognizes it is unlikely to win as many delegates in Texas. But although some of Texas' 155 delegates are awarded statewide, most are distributed via congressional district: a candidate who earns more than 50% in one of the state's districts wins all three delegates in the district, and anyone who earns below 20% wins zero. So if Rubio's camp can surgically target Cruz and minimize his vote percentage in key districts, they can keep him from building a delegate lead on Super Tuesday.

"You can get nowhere near first place in Texas and still vacuum up a whole lot of delegates just because of the size of the state," said Todd Harris, Rubio's chief strategist. "We're under no illusions that there won't be a resounding Ted Cruz victory, but there are things that we think we can do on the margins to sweep up some delegates -- and we're going to do it."

Home in Houston

Cruz received a hometown hero's welcome at the Lincoln Reagan Dinner on Wednesday evening, where his stickers firmly stuck to guests' blazers.

That dominance wasn't always a sure thing.

A year ago at this same dinner, the question in this city in the pre-Trump era was which of the men who have called it home would emerge victorious: Would it be Jeb Bush, whose father remains revered here by both Democrats and Republicans alike? Rick Perry, the powerful, 14-year governor? Rand Paul, who grew up in a nearby suburb? Or Cruz, who headquartered his campaign not far from his condominium?

Or maybe an outsider: Scott Walker, who wowed as a keynote speaker here eleven months ago with odes to Reagan and who Abbott said governed "like a Texan" in Wisconsin.

The threat to Cruz has indeed been an outsider, but one that no one in this booming oil city saw coming.

So in the final days of the Texas primary, Cruz is looking to remind them of their shared roots. As he collected Abbott's endorsement in a factory on Wednesday afternoon, Cruz's rhetoric was awash with Texas pride and symbolism, calling on his constituents to cast aside their fascination with the New Yorker they love and vote for the Texan they know.

"We are not a people who are impressed by a lot of blustery rhetoric that's not backed up by truth," Cruz said. "We can't be fooled by P.T. Barnum. The time for the clowns and the acrobats and the dancing bears has passed."