Cruz's orbit is eyeing an eventual three-man race between the Texas senator, Donald Trump and Rubio that shows no signs of consolidating quickly, according to conversations with nearly a dozen people tied to the campaign.
A few ways to clear the field more and make Rubio's path even harder: Raise money. Remove Ben Carson from the race. And punish rivals in South Carolina with a harshly negative, military-themed pitch.
"Maybe you should vote for more than just a pretty face," one of the people featured says.
Cruz won the Iowa caucuses and finished third in New Hampshire, and Republican donors have slowly expressed more openness to Cruz than they were just a few weeks ago, but Cruz fundraisers say few have hopped over fully to join the finance squad that left them with more money in the bank than any other campaign.
"There's a whole lot of people are who just holding back," said Cruz fundraiser Bryan Hardeman. "You got all these damn also-ran candidates that just don't have a chance in the world, and that kind of holds people back."
Added another top Cruz ally in close contact with the campaign: "The low-hanging money is pretty much all gone."
Until the field has more clarity, though, those checks may not arrive. Top Cruz allies and donors stress that their main objective is turning the GOP race into a one-on-one battle with Trump.
"For us, it's got to get down to a two-man race as soon as possible. Our issue is not Trump, our issue is Rubio," the person said. "We'll pick one focus and try to take that one person out -- and right now, that needs to be Rubio."
As much as Cruz's world is eager for the Republican race to become a two-man race, it is not yet.
"The winnowing process has to happen quickly," said another person close to the campaign. "The longer it drags on, the more difficult it is for Ted to do what he needs."
Tuesday evening was a strategic victory for Cruz: Much of the establishment is likely to remain in the Republican race after the results, complicating Rubio's path. Cruz's campaign pounced on Rubio's fifth-place finish in New Hampshire. The Florida senator now enters South Carolina beleaguered, and less close to winning over the establishment "bracket" than it was 24 hours ago.
But the New Hampshire results, especially John Kasich's second-place showing, means the race will continue to be cluttered for the rest of the month.
Cruz reiterated Wednesday that he's the only Republican who has shown the strength to beat Trump, and again called for primary voters to group themselves into pro-Trump and anti-Trump camps. Cruz promised to pillory Trump in the state from his right: "You can't beat Donald Trump running from the left," he told reporters there on Wednesday.
And his chief strategist, Jason Johnson, framed South Carolina this way: "It becomes more of a two-man race. And in that two-man race, we're 1-and-1."
But the corresponding national fundraising infrastructure is still clicking into place -- top donors have still been largely slow to jump on the Cruz bandwagon, while others are beset by a number of at-times conflicting pro-Cruz super PACs that are not yet equipped to land large donations.
Hardeman predicted that wallets would open if Cruz has a strong showing in South Carolina and rivals leave the race. His campaign had $19 million in the bank as of Dec. 31, more than any other GOP rival by more than $8 million.
Cruz's network of occasionally clashing super PACs aren't actively meeting the fundraising challenge either, even for donors interested in the Texas senator.
Keep the Promise, the main umbrella of pro-Cruz groups, is encountering a flurry of eager donors after Cruz's victory in Iowa, sources say -- but since it does no active soliciting, it has not yet turned that newfound interest into cash in the bank account.
And a separate, newer super PAC, Stand for Truth, only just hired a professional fundraiser, Kate Doner, CNN has learned. Doner was the longtime fundraiser for Wisconsin Gov. Scott Walker, and she has deep connections to many of the major, high-dollar donor networks in Republican politics.
A number of GOP megadonors have indicated a willingness to back Cruz. Las Vegas casino titans Sheldon Adelson and Steve Wynn both gave the maximum they could to the campaign during the last campaign fundraising quarter, yet neither of the magnates has given large checks to the pro-Cruz super PAC effort. And even the billionaire Deason family, which has endorsed Cruz, has not given to a super PAC.
Ben Carson still poses a threat
Cruz's world is trying to lower expectations for the Palmetto State, resisting resting its laurels on South Carolina, recognizing that it must not lose focus of Super Tuesday, March 1, on which some hope the campaign can win about 60% of the delegates to be won then. The home state of Texas remains the core of the Cruz firewall.
The center of Cruz's campaign in South Carolina likely to focus on military issues. Cruz in the lead-up to New Hampshire uncorked a new line of attack on Rubio, one of several candidates who recently agreed that women should be eligible for a military draft. And Cruz campaign aides have mentioned that Trump received deferments from service in the Vietnam War, a line of attack that could resurface in military-friendly South Carolina.
Evoking ire of some top Cruz backers: Ben Carson, who has moved from a national competitor to a political nuisance for them as he shows an unwillingness to leave the race despite falling poll numbers, blocking Cruz's efforts to coalesce the Christian right.
A lingering Carson, in the eyes of those close to the campaign, could deprive Cruz of voters almost certain to break for them, especially in the South. Carson appears to still have a steady floor of support, and even if he is highly unlikely to eclipse delegate thresholds in the southern states, his appeal there could steal delegates away from Cruz, some worry.
"He can do damage if he wants to, but he would be damaging his own beliefs and ideas if he does that," Patrick Moran, a Cruz donor and friend from Houston, said of Carson. "I hope he has the insight to see that and step back from the fact that this is personal. It gets that way, and if you aren't ready for that, then maybe you shouldn't be running for president."