The Texas firebrand is now squarely in the crosshairs, dealing daily with attacks from Republicans and Democrats in a way that he shied from for much of the race. And he's punching back.
In perhaps the clearest signal yet that Cruz has arrived in the top tier, Democrats are training their eyes on him for the first time, with a preview of the message to expect from them should he win the GOP nomination.
"Noisy Xenophobe Steve King Endorses Fellow Noisy Xenophobe Ted Cruz," read one subject line emailed to reporters this week from the Democratic National Committee, after the Iowa congressman announced his backing for Cruz. "Ted Cruz's extreme vision to create an unrecognizable America," read another from a Hillary Clinton super PAC the week prior.
Republicans struggling to gain any traction or media attention at all are turning their guns at Cruz in much the way that back-of-the-pack hopefuls have done so at Trump. Rick Santorum has loudly questioned Cruz's conservative credentials, arguing his now-abandoned plan to increase legal immigration should disqualify him with the base. Bobby Jindal had challenged Cruz to a one-on-one debate on Obamacare, before dropping out.
And an interview last week, Jeb Bush dinged Cruz for a vote that he said showed Cruz was insufficiently tough toward Islamic extremism.
"We had two United States senators -- three -- their views at the time were that it wasn't our fight," the former Florida governor said about a 2013 vote to the Union Leader's editorial board. "Ted Cruz said something to the effect that, 'I don't want to provide the air force power for ISIS.' That's basically his argument."
Cruz on offense
Cruz's reluctance to engage rivals diverges wildly from a Republican race that for eight months has been defined by the pugnaciousness of Trump and the largely feeble, desperate rhetoric from rivals trying to dethrone him. White House hopefuls have called one another a "cancer on conservatism," ridiculed the physical looks of competitors on national debate stages, and alleged that traumatic events from rivals' childhoods really didn't happen.
He has for the most part been extremely disciplined about opening new fronts of attack, especially ones with Trump and Carson that can so easily backfire. He has often expressed condescension over what he sees as media-spawned firestorms -- in Harlan, Iowa, Cruz chided rivals who "go out of their way to smack Donald with a stick."
Yet at a town hall in South Carolina last weekend, Cruz for the first time called his new immigration plan "the most aggressive of any candidate in the race," perhaps a warning shot to Trump, who has looked to position himself as the GOP fray's most restrictionist voice.
"Well, listen, I'm a big fan of Donald Trump," Cruz told reporters when asked in Sioux City about a Trump statement in an answer that routinely would have just stopped there. "But I'm not a big fan of government registries of American citizens."
Stumping in churches across South Carolina earlier this month, the son of a pastor argued that he was better qualified than candidates like Carson to stand up for religious liberty, which the campaign sees as a key contrast point with the Republican field.
And with Rubio, he has a new foil. Since the last Republican debate, Cruz has repeatedly and eagerly laid into Rubio on immigration and his role in the failed "Gang of Eight" comprehensive immigration bill.
Cruz is happy to remind voters about Rubio's support for sugar subsidies.
"It is an example of the Washington cartel," Cruz told reporters in South Carolina earlier this month. "It's making politicians fat and happy, but it's picking a handful of favorite corporate winners and making the American people, the taxpayers and the consumers, the losers."
Rubio, for his part, is using Senate colleague Cruz as his latest straw man. Here in Iowa on Saturday night, Rubio spoke for about an hour without taking any hits at Cruz, or any opponent. Then, landed on the difference du jour -- Rubio says some Republicans like Cruz have hamstrung the abilities of American intelligence officials.
"If God forbid, tomorrow morning there is a terrorist attack on the United States, the first question that we hope to answer to is, 'Why didn't you know about this and why didn't you stop it?' And the answer better not be because a program" had been gutted, Rubio said. "There are even people in my party that know better than that."
How much Cruz will continue to press the contrast is an open question. He has previously waited for Trump and Carson to collapse, but that hasn't happened. His super PACs, the Keep the Promise groups, are carefully monitoring Trump's crowd sizes in states like Iowa and Texas, but asked how they would handle Trump, a leader of the groups said: "Wake up every morning and take the Hippocratic oath. Do no harm."
Cruz has long said he believes there is a season for policy differences -- one that he seems willing to tiptoe toward, but even if not totally wading in.
When asked by CNN though what exactly he was waiting for before outlining policy differences in this new "season," Cruz, in form, told the media to stop egging on Republican-on-Republican violence. And sitting one seat to Carson's right at a high-profile evangelical forum here in Iowa on Friday night -- the exact venue where Cruz could differentiate himself from the reserved, retired neurosurgeon -- Cruz offered little.
"It's down to splitting hairs to find the differences between them sometimes," said Gary Pitts, a Rubio supporter who lined the perimeter of the stage to hear him here.
"They all like each other," his wife, Shelly, chimed in. "It's just politics."