Republican presidential candidates Ben Carson, Sen. Ted Cruz and Sen. Marco Rubio wait to begin the Republican presidential candidate debate in Des Moines. (Daniel Acker/Bloomberg)

The first Republican presidential debate without Donald Trump still took on a Trumpian tone at times, with the seven other top candidates here Thursday night voicing anger, talking tough and vowing to do away with political correctness.

But with the defiant GOP front-runner staging his own counter-program by rallying supporters a few miles away, Trump’s absence left a vacuum on the debate stage and fewer fireworks than Republicans had grown accustomed to.

From the opening question, it was mostly filled by Sen. Ted Cruz (Tex.), who has been locked in an intensifying duel with Trump for dominance in Iowa’s first-in-the-nation caucuses, only four days away.

Cruz began by mocking Trump’s reputation for insults: “I’m a ‘maniac’ and everyone on this stage is ‘stupid,’ ‘fat’ and ‘ugly.’ And Ben [Carson], you’re a ‘terrible surgeon.’ Now that we’ve gotten the Donald Trump portion out of the way . . .”

From there, however, little more was said about Trump, few direct attacks were leveled at him and the overall atmosphere was notably calmer than in previous debate. That left Cruz as the top target as Sen. Marco Rubio (Fla.) and other opponents sought to puncture the Texas senator’s appeal by trying to depict him as an inauthentic conservative.

Republican presidential candidates weighed in on immigration, the Islamic State, criminal justice reform and - of course - Donald Trump at the Fox News debate in Des Moines, Iowa on Jan. 28. (Sarah Parnass/The Washington Post)

“The truth is, Ted, throughout this campaign you’ve been willing to say or do anything in order to get votes,” Rubio said. “You want to trump Trump on immigration.”

Rubio and Sen. Rand Paul (Ky.) both attacked Cruz for having once supported an amendment that would have granted legal status, not citizenship, to illegal immigrants — though Cruz maintains that it was a “poison pill” and that he has always opposed amnesty.

“He is the king of saying, ‘Oh, you’re for amnesty. Everybody’s for amnesty except for Ted Cruz,’ ” Paul said. “But it’s a falseness, and that’s an authenticity problem.”

Cruz was not the only candidate on the defensive on immigration, however. Rubio also came under fire for his role as one of the Gang of Eight senators who crafted comprehensive reform legislation in 2013.

After giving Rubio a backhanded compliment for being “charming and smooth,” Cruz hammered him for having aligned with President Obama and Democratic Senate leaders Harry Reid (Nev.) and Charles E. Schumer (N.Y.).

The Fox News Channel moderators tried to challenge both Cruz and Rubio by playing archival video footage of the two senators. After showing the Cruz videos, co-moderator Megyn Kelly asked: “Was that all an act? It was pretty convincing.”

In the absence of Trump, Cruz and Rubio had the most to gain or lose in Thursday night’s debate. The two are the second- and third-polling candidates in Iowa, and their strategies are predicated on being the last non-Trump candidate left standing to face off with the mogul in a long-slog primary season.

Both men emerged with scars.

Rubio appeared to struggle explaining why he advocated a hard-line immigration approach as a Senate candidate, then pursued comprehensive reform that included a path to citizenship for illegal immigrants, then reverted.

Rubio said he does not support “blanket amnesty” and focused on the need to seal the border with Mexico and improve security there.

Former Florida governor Jeb Bush used the exchange to portray Rubio — his onetime protege when Rubio was a Florida state lawmaker — as weak for having reversed positions on immigration. After noting that he supported Rubio’s work in the Gang of Eight, Bush said, “He cut and run because it wasn’t popular among conservatives, I guess.”

“You shouldn’t cut and run,” Bush said. “You should stick with it. That’s exactly what happened. He cut and run, and that’s a tragedy.”

Rubio countered by saying that Bush had reversed his own position on citizenship and legal status in a book he wrote.

“So did you,” Bush snapped back.

New Jersey Gov. Chris Christie used the back-and-forth over Senate votes and amendments to show the leadership differences between legislators and executives, and he repeated his call for a governor in the White House.

“I feel like I need a Washingtonese-English dictionary converter,” Christie joked.

Carson, the retired neurosurgeon who once led the polls but has seen his lead falter among heavy scrutiny of his policy knowhow, invoked his medical career as a credential for the White House: “I’ve had more 2 a.m. phone calls than everybody here put together, making life and death decisions.”

The immigration exchange was one of the few moments of direct confrontation onstage between the candidates. The debate lacked a central focus, with Kelly and her co-moderators, Bret Baier and Chris Wallace, asking many one-off questions that focused on the vulnerabilities of individual candidates.

In return, the candidates gave many of the canned lines that have become familiar on the campaign trail, avoiding taking big risks with the Iowa caucuses so close.

The seventh Republican debate of the 2016 campaign cycle was the first not to include Trump, the billionaire mogul whose bombast and showmanship dominated the previous events.

Trump boycotted the debate, escalating his feud with Fox and its star anchor, Kelly, because he believed he would not be treated fairly. He has long harbored disdain for Kelly because of her aggressive line of questioning during the first GOP debate in August, and he has argued that the network was taking advantage of his popularity with viewers to boost its ratings and thus its advertising revenue.

In her opening question, Kelly said, “Let’s address the elephant not in the room tonight.”

Trump staged a competing rally Thursday night on the Des Moines campus of Drake University, where he raised money for and honored veterans.

Much of the debate centered on foreign policy, with the candidates competing to show who would be the toughest commander in chief.

“You claim it is tough talk to discuss ‘carpet bombing,’ ” Cruz said. “It is not tough talk. It is a different fundamental military strategy than what we’ve seen from President Obama.”

Early in the debate, Cruz took fire on multiple fronts. Paul went after him for refusing to show support for a vote to audit the Federal Reserve and for not voicing strong enough opposition to the government’s surveillance efforts.

“I don’t think Ted can have it both ways. They want to say they’re getting some of the liberty vote,” Paul said. “But we don’t see it happening at all. We think we’re going to do very well in Iowa with the liberty vote.”

Rubio, as he has for months, portrayed Cruz as weak on national security.

“As already has been pointed out, the only budget that Ted has ever voted for is a budget that Rand Paul sponsored that brags about cutting defense spending,” Rubio said. “And I think that’s a bad idea.”

The closing days of the race have been nasty here in Iowa. The campaigns and allied super PACs are blanketing television and radio airwaves with attack ads, while the candidates have laced their stump speeches with sharp barbs.

Ohio Gov. John Kasich, who is banking his hopes on the Feb. 9 New Hampshire primary, sought to position himself above the fray.

“We cannot fix things in this country — the Social Security, the border, balancing the budget, getting wages to grow faster — unless we lead as conservatives, but we also invite people in from the other party,” Kasich said. “We have to come together as a country. And we have to stop all the divisions.”

Kasich’s call for unity went unheeded, and he was a non-factor through significant stretches of the debate as other candidates sparred.

As in previous debates, the candidates harshly attacked Hillary Clinton and sought to position themselves as best equipped to lead the Republican Party into the general election against Clinton, whom they see as the most likely Democratic nominee.

“She is not qualified to be president of the United States,” Christie said, drawing loud cheers from the audience. “The fact is, what we need is someone on that stage who has been tested, who has been through it, who has made decisions, who has sat in the chair of consequence and can prosecute the case against Hillary Clinton.”

Bush made a similar pitch.

“This is an election about people that are really hurting,” he said. “We need a leader that will fix things and have a proven record to do it. And we need someone who will take on Hillary Clinton in November.”

David A. Fahrenthold in Washington contributed to this report.