By MATT FLEGENHEIMER & JONATHAN MARTIN – NYTimes

[Ashley Parker contributed reporting from New York.]

Senator Ted Cruz emerged from Tuesday night’s Republican debate later largely unscathed, weathering attacks from Senator Marco Rubio, avoiding them from Donald J. Trump and giving little reason to doubt that his rise among Tea Party and evangelical voters will continue.

The Texas senator’s steady performance in the debate seemed likely to solidify his ascendant standing in Iowa, where he has surpassed Mr. Trump in some recent polls.

While the candidates pressed their cases in interviews on Wednesday and prepared to set off on the last stretch of campaigning before a likely holiday lull, the debate seemed to confirm the volatility of the race in New Hampshire and beyond, adding little clarity as to which man or woman might emerge as the favorite among center-right Republicans.

Mr. Trump, who leads in national polls, slogged through an uneven night, though forgettable debate performances have in the past had little effect on his support. Perhaps most notably, Mr. Trump resisted repeating past criticisms of Mr. Cruz during the debate and in interviews afterward. For days before the debate, Mr. Trump had assailed Mr. Cruz, who questioned the billionaire’s judgment at a private fund-raiser last week but who has remained publicly deferential. Yet Mr. Trump cast aside any strategic imperative to halt Mr. Cruz’s momentum in Iowa, continuing his habit of holding fire on somebody unwilling to attack him first onstage.

Donald J. Trump, center, repeating past criticisms of Ted Cruz, right, during the debate and in interviews afterward. (Credit: Ruth Fremson / The New York Times)

“I just think he didn’t say anything that I particularly disagreed with,” Mr. Trump told CNN after the debate.

After facing two forces to which he is unaccustomed — an often unsympathetic crowd and an effectively pugnacious Jeb Bush — Mr. Trump planned on Wednesday to return to his campaign comfort zone with a midday rally in Mesa, Ariz.

Mr. Bush, meanwhile, appeared energized, beating rivals to the cable airwaves from Las Vegas in a slew of interviews around 4 a.m. Pacific time.

After appearing to irritate Mr. Trump in a series of exchanges during the debate, a triumph that bordered on catharsis for many supporters of his long-languishing campaign, Mr. Bush and his team moved quickly to convince donors that he was seizing the momentum from his pointed attacks on the developer.

“I don’t think he’s a serious candidate — I don’t know why others don’t feel compelled to point that out, but I did,” Mr. Bush said Wednesday on CNN, adding, “Donald Trump is not going to be president of the United States by insulting every group on the planet, insulting women, P.O.W.s, war heroes, Hispanics, disabled, African-Americans.”

Mr. Bush’s performance on Tuesday was particularly sweet for a campaign whose candidate had flubbed a memorable confrontation with Mr. Rubio in a previous debate.

“We know debates do matter,” Sally Bradshaw, one of Mr. Bush’s top advisers, told donors on a conference call immediately after the debate. “We have seen the downside of that. I think we can celebrate tonight that we’ll see the upside of that.”

Mr. Bush, who was scheduled to hold a private gathering with supporters in Nevada on Wednesday, now finds himself tussling on two fronts in New Hampshire, a state increasingly viewed as decisive for his fortunes: In addition to Mr. Trump, Mr. Bush must contend with establishment favorites like Mr. Rubio and Gov. Chris Christie, who had another strong showing on Tuesday and who has been rising in polls in the state, which holds the nation’s first primary, on Feb. 9.

There is also Gov. John Kasich, whose “super PAC” was to begin running ads in New Hampshire on Wednesday criticizing Mr. Christie’s fiscal record. It is at once an acknowledgment of Mr. Christie’s renewed strength there and a signal of that state primary’s present chaos.

“For the jumbled-up establishment lane, it’s now even more congested,” said Matt Strawn, a former Iowa Republican chairman. “And Cruz’s lane is totally clear.”

Mr. Rubio, coming off another broadly well-received debate performance, plans to appear on Wednesday at rallies in both Iowa and New Hampshire. For the second consecutive debate, the focus afterward centered in large measure on Mr. Rubio and the party’s approach to immigration policy.

Mr. Cruz, who has since the last debate repeatedly highlighted Mr. Rubio’s past support for bipartisan immigration reform that included a pathway to citizenship, sought in television interviews to tie the Florida senator’s position to recent terror threats.

Jeb Bush with his wife, Columba, after the debate. (Credit: Ruth Fremson / The New York Times)

“This is one of the first times we really discussed how the Rubio-Schumer amnesty plan would have endangered our national security,” Mr. Cruz said on Fox News, referring to Senator Chuck Schumer, the New York Democrat. (Mr. Rubio, appearing Wednesday on Fox News, also invoked the liberal senator while criticizing Mr. Cruz’s support for limits on surveillance programs, saying Mr. Cruz had “aligned himself with Barack Obama and Chuck Schumer and the A.C.L.U. and every other liberal group in America.”)

Mr. Cruz told CNN that the confrontations with Mr. Rubio were unsurprising because “Senator Rubio’s campaign has been running attack ads against me, and I think they’re concerned” at the prospect of conservatives’ uniting around Mr. Cruz.

But Mr. Rubio’s campaign has reveled since the debate in what it saw as a mealy-mouthed response from Mr. Cruz to a question about whether he could support legal status for people in the country illegally.

“I have never supported legalization,” Mr. Cruz said, countering a claim from Mr. Rubio, “and I do not intend to support legalization.”

Mr. Rubio’s communications director, Alex Conant, said on Twitter, “After this debate, I don’t intend to celebrate too much.”

Michael Meyers, a veteran Republican strategist, said that Mr. Rubio “proved he could handle some punches” on a night when Mr. Cruz and Senator Rand Paul often teamed up to knock him. But Mr. Rubio, Mr. Meyers added, “didn’t prove he could really sting Cruz.”

The Cruz-Rubio dynamic appears to be growing more confrontational beyond the debate stage, as well. Republicans in Iowa this week received their first piece of mail from Mr. Rubio’s super PAC criticizing Mr. Cruz for his vote to limit the National Security Agency’s metadata program. (Mr. Cruz has said an alternative program had, in fact, strengthened the country’s ability to fight terrorism.)

“These men undermined our intelligence agencies’ ability to stop terrorist attacks,” the mailer reads, below a photo of Mr. Cruz, Mr. Paul, President Obama and Senator Harry Reid.

Yet in a sign of how reluctant the candidates and their allies are to imperil their own prospects by going aggressively negative, the literature points to the efforts of Senator Tom Cotton of Arkansas, not Mr. Rubio, to protect robust surveillance laws.

For others, the debate — the last major scheduled event for Republican candidates this year — prompted fresh questions about the viability of their campaigns.

Carly Fiorina, appearing Wednesday on CNN, chafed at a remark about her struggles in the polls. “Oh wow, you’re like declaring an end to my candidacy,” she said. “I think we’re just getting started.”

Minutes later, Senator Lindsey Graham, who was considered a standout by many in the so-called undercard debate of lower-polling candidates, made a pitch to viewers after a questioner noted that he was funny.

“I am hilarious — send money, if you want to keep me in this race,” he said, adding, “I’m not speaking again until somebody sends $100,000.”