When Sen. Ted Cruz walks on stage for his fifth presidential debate Tuesday in Las Vegas, it will be his first as the center of attention.  

The Texas Republican, who has been reluctant to publicly go after front-runner Donald Trump, is now closing in on him in two polls of likely Iowa caucus voters released over the weekend. One of them, commissioned by the Des Moines Register , showed Cruz with a 31 percent to 21 percent lead over Trump, while another, commissioned by Fox News, showed him with a 28 percent to 26 percent lead. “At this point, this competition is to get the voters’ attention. In Iowa, Cruz has done it the old-fashioned way with a strong ground game and by steadily building,” said David McIntosh, president of the conservative Club For Growth. “The debate will be a big test for him.”  

In previous debates, Trump has gone on the attack against those who have challenged him, mocking Kentucky Sen. Rand Paul for his looks and his poll numbers  and former Florida Gov. Jeb Bush for his energy level . Cruz, on the other hand, has approached the matchups as the seasoned debater he is, focusing his barbs on the media while mostly sticking to his own campaign message.  

“There’s no reason for Ted Cruz to change what he’s doing — it’s working,” said Amanda Carpenter, a Republican writer and operative who worked for Cruz from 2010 until this June,  most recently as his communications director.  

Cruz’s rise in Iowa came as he made his way into popular culture in a big way. On Dec. 12, he was lampooned by NBC’s “Saturday Night Live ” — and got the kind of skewering usually reserved for the top candidates. Even though Cruz led Trump in the Hawkeye State, Trump solidified his status as the national front-runner with a 27-point lead , according to Monmouth University on Monday.  

Tuesday evening,
Trump will be flanked onstage  by Cruz and retired neurosurgeon Ben Carson, the last person Trump viewed as a challenger to his lead in the polls. But beyond Carson, with Trump’s dominance in Iowa in question, McIntosh said conservatives like him are looking forward to the debate that could start playing out between Cruz and his colleague from Florida, Sen. Marco Rubio.  

Carpenter said the fight between her former boss and Rubio may be most vivid on issues of national security.  

“I don’t think Donald Trump can hang with the discussion” Cruz and Rubio could have “on the constitution, due process, and the role of surveillance,” she said.  

Only Rubio has been willing to jab Trump publicly, while Cruz has done so only at private events. According to leaked audio obtained by the New York Times , Cruz only went so far as to question the “judgment” of both Carson and Trump. Trump fired back and called Cruz “a little bit of a maniac .”  

https://twitter.com/realDonaldTrump/status/676167468780412929  

McIntosh said candidates such as Cruz, Rubio and Carson have found opportunities to rise in the polls in part thanks to his group’s negative commercials against Trump.  

The candidates who have taken shots at Trump, like former Florida Gov. Jeb Bush and Ohio Gov. John Kasich, have not seen success. “One of the reasons the Club for Growth spent $1 million and told the truth about Trump,” McIntosh said, “was because it was hard for any of the candidates to do without looking self-serving and getting the bounce back on the negative. We’re not on the ballot and we figure we can send a message.”