(CNN) Ted Cruz is facing a fresh, intense and public wave of criticism about his campaign strategy from some of his highest-profile supporters, a backlash that comes as he prepares for the biggest day of his political life: Super Tuesday and its slew of Southern primary states.

The cry from surrogates, fundraisers and operatives close to the campaign is simple: be the strong conservative you are and execute an abrasive, scorched-earth campaign battle against Donald Trump.

"Stop telling us how much you like Trump personally," Iowa radio personality Steve Deace, one of the most visible Cruz surrogates and a man Cruz credited from the stage at his victory party, wrote in a Conservative Review op-ed . "That's typical GOP unity speech, and people don't want typical GOP unity speech. They want their darned country back, which is why they're aligning with the most divisive, craptastic figure ever to attempt to run for president."

"Ted needs to be the crusader against Washington that he is. That's it. Nothing more cute than that," tweeted Amanda Carpenter, a former top aide in Cruz's Senate office who is now a CNN contributor.

"It is time to expose Trump," one pro-Cruz fundraiser, granted anonymity to candidly assess the campaign, told CNN.

The worries come after Cruz finished third in South Carolina, where evangelical or born-again Christians made up 74% of the GOP electorate . Making things worse for Cruz, Trump captured all of the 50 delegates up for grabs. If Cruz can't win one delegate with demographics like that, the fears are Super Tuesday won't be much better without a change in tactics.

In the eyes of the frustrated, Cruz has been unable to effectively neutralize Rubio and turn it into a genuine two-way race. Rubio's second-place showing in South Carolina has made him into a threatening candidate who has shown the ability to drag Cruz into the mud and strip votes away from Republicans anxious about nominating Trump.

"Cruz's messaging is a muddled mess," Erick Erickson, a conservative commentator close to both Cruz and Rubio's campaigns who is neutral between them, wrote Monday. "For about eight months I have said it was Cruz's race to lose. Now I think it is Rubio's race to lose. The race has shifted in Rubio's favor. Republicans want to beat Trump and Rubio is seen by many of them as the likable, electable alternative."

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Cruz has showed signs of change. After months of not attacking Trump at all, Cruz has launched an aggressive paid media campaign that targets him as a fake conservative, and Cruz now needles Trump repeatedly on the stump before voters.

But his campaign stumbled Monday when he fired communications director Rick Tyler after Tyler distributed a video that falsely depicted Rubio as dismissing the Bible. The incident comes as Trump, Rubio and Ben Carson hit Cruz as a liar willing to say anything to win.

"The Cruz campaign has to focus on getting basic campaign techniques right," said a Republican operative who works for the presidential campaign, who asked not to be identified. "I don't think Cruz can win the nomination at this point. I think his campaign is done."

Still focused on Rubio

And he can't completely turn away from Rubio. His advertising has been just as centered as on targeting Rubio, and Cruz's aides at times appear close to obsessed with thwarting Rubio's ascendance into a top-tier candidate.

Cruz defenders still believe the map favors them over Rubio as it heads below the Mason-Dixon Line, and his team labored on Monday to reset the narrative in the South. They blamed the media for holding Rubio to low expectations, and for holding Cruz to a high bar. Tyler, before he was fired, said Monday that South Carolina's results offered no omens in other southern states without the same "pockets of liberalism."

And his campaign released a memo Monday evening from chief strategist Jason Johnson. Titled "Ted Cruz is the only candidate who can defeat Trump," Johnson's focus is primarily on the idea that Rubio is not positioned to take on Trump, no matter how many financial resources he has, because the Florida senator is too moderate.

"Ted Cruz is substantially outperforming Rubio, and in many cases beating Trump, for the Republican base vote. The core of the party is with Cruz and may not be with Rubio head-to-head against Trump," Johnson wrote. "The battle for conservative voters is clearly between Cruz and Trump, with Cruz winning one state and Trump edging out Cruz in the other two; Rubio lags behind in all three."

And, Cruz added to reporters Monday in Las Vegas, when other candidates attack him, it's possible they could hand Trump the nomination.

"I believe that Donald Trump will not be our nominee, but the only way to beat him is for conservatives to unite behind our campaign. If other candidates devote all their time and energy to attacking us, to engaging in personal slurs and attacks, it is possible they could weaken us to sufficient extent that they could hand Trump the nomination."

Cruz still enjoys many advantages over the rest of the field: Cruz and his super PACs together had $38 million on hand as of Jan. 31, a $27 million advantage over Rubio and his groups that could pay dividend as the race grows expensive and national.

And Rubio is hardly on a glide path to the nomination as it enters more conservative terrain. But the Florida senator won over almost a dozen endorsements in the 48 hours after South Carolina and Bush's departure from the race.

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Almost immediately after the Palmetto State disappointed Cruz's campaign, aides were quickly pointing to delegate-rich Texas as a state that would revive his southern strategy, raising the stakes for a state where early polling nevertheless shows a difficult race. Cruz's home state has always been seen as the jewel of Super Tuesday, but the increasingly urgent focus suggests narrower ambitions than the hopes of some Cruz supporters to once win 60% of the delegates up for grabs on March 1.

Nevertheless, Cruz's strategy that is now being publicly questioned like never before -- even by run-of-the-mill supporters.

Ahmed Diab, a 24-year-old grassroots Cruz supporter from Virginia, said the senator "really disappointed me" in South Carolina.

"To be honest, I don't see any path for Cruz to the nomination at all," Diab said. "The way I see it is that the only scenario where Trump doesn't get the nomination is if Cruz dropped after Super Tuesday and Rubio started winning in a two-man race."