In South Carolina, Cruz’s team is scaling up the data-driven ground operation that propelled it to victory in Iowa. The campaign’s Iowa state director, Bryan English, is on the ground here coordinating with key surrogates, and a second Camp Cruz location at a Quality Inn & Suites in Greenville opened its doors on Monday.

South Carolina presents a critical test for Cruz, whose campaign will rise or fall on the extent of his success in uniting the GOP’s evangelical and tea-party factions, both strongly represented here and across the rest of the South. After Georgia secretary of state Brian Kemp led a successful effort to convince Georgia, Tennessee, Oklahoma, Alabama, Arkansas, and Cruz’s native Texas to band together and hold their nominating contests on the same day — Super Tuesday, March 1 — Cruz saw an opportunity to amass delegates and momentum early in the nominating process. He has made no secret that he believes his path to the nomination runs through the South, and he has gone so far as to call it his “firewall.”

South Carolina, which votes Saturday, will give a good indication of just how sturdy that firewall is. The state is demographically similar to its southern neighbors, with both a large evangelical population (evangelicals constituted nearly two thirds of Republican primary voters in 2012) and a strong tea-party presence. A loss here would be a warning sign that the campaign has overestimated its ability to identify and persuade the voters it needs to carry the South…

Campaign manager Jeff Roe says he’s had staffers on the ground in South Carolina — many more than he had in Iowa — for ten months. He expects over 700,000 voters to cast ballots in Saturday’s primary, as compared to the 186,000 who voted in Iowa, and he says the campaign has prepared for the increase in scale by ramping up its presence on television. While Cruz’s team spent just $2.5 million in Iowa, a fraction of what rivals Jeb Bush and Marco Rubio shelled out there, they’ve already spent $2.4 million in South Carolina. That’s still a fraction of what Cruz’s rivals are spending in the state, but his team is not yet done buying ad time here. The money has gone into attacks against both front-runner Donald Trump and Rubio, who is running third behind Trump and Cruz in most polls. The Florida senator is clearly in Cruz’s rear-view mirror. “Any time one attacks two and two attacks one, there’s always a chance that everybody gets sick of it and goes to number three,” says a Cruz adviser.