In the fourth and final Republican presidential debate of the year, the narrow policy differences among the candidates were overshadowed by feisty personal clashes and insults.

With the Iowa caucuses six weeks away, those who watched the proceedings noted how former Gov. Chris Christie and Vivek Ramaswamy freely and loudly aired their grievances, while former Ambassador Nikki Haley — whose star has been rising — carefully tried to deflect incoming fire and for the most part emerged unscathed. Gov. Ron DeSantis, whose campaign has experienced some upheaval amid sliding poll numbers, delivered what many observed was his strongest performance to date, pressing Ms. Haley on her Wall Street donors and ties to corporate America while easily fending off his other foes.

But the two hours of debate once again featured few sharp attacks on former President Donald J. Trump, leaving political strategists and pundits believing it is most likely too late to topple the front-runner.

Here is a sampling of the reaction.

“Ron DeSantis is getting more comfortable with each debate. You could see him getting his sea legs as the debate went on. He was clearly more fluent and nimble on the cultural issues,” said Matt Gorman, a Republican strategist and former senior adviser to Senator Tim Scott’s presidential campaign.

“DeSantis did the most good for his campaign tonight and NewsNation is unquestionably the big winner. By far the best debate because the moderators actually asked about issues that the Republican base care about,” said Megan Basham, a Claremont Institute fellow and writer for the conservative website The Daily Wire.

“Chris Christie and Nikki Haley gave solid performances. Christie’s no-holds-barred approach is what many operatives have expected since the first debate. Nikki Haley once again showed she can hold her own amongst a barrage of attacks, but that’s a far cry from beating Donald Trump,” said Lance Trover, a Republican strategist who was press secretary to Gov. Doug Burgum of North Dakota.

“Nikki Haley’s policy and rationale-heavy performance illustrated clearly why top-dollar Republican donors are pinning their last-hurrah hopes for a non-Trump nominee on her in the final weeks of the primary season. DeSantis, Christie and Ramaswamy aided that effort by spending more time attacking her than offering reasons for their own candidacy,” said Henrietta Treyz, managing partner and director of economic policy research at the consulting firm Veda Partners.

“I don’t think the hits on Haley from DeSantis and Ramaswamy stung very much. At least on the topic of China, there seemed to be a broad sense of unity among the candidates,” said Eswar Prasad, a professor of trade policy at Cornell University.

“Governor Christie is the only one running against Trump. His answers have at least attempted to eat into the lead of the guy who is 40 points ahead. The rest are just padding that lead,” said Michael Steele, the former chairman of the Republican National Committee.

“Defending a competitor under fire is a tried-and-true debate tactic — feels unexpected to the audience and makes you seem human. Christie seemed to also genuinely enjoy utterly nuking Vivek in defense of Haley, which earns him extra points on the execution,” said Kate Bedingfield, former White House communications director in the Biden administration.

“None of the candidates onstage did anything to hurt Trump or change the fundamental dynamics of this race. If anything, candidates like DeSantis and Ramaswamy alienated voters tonight, losing ground when they can least afford it. For Haley, the most important narrative right now is that she’s on the rise,” said Caitlin Legacki, a Democratic strategist and former adviser to Commerce Secretary Gina Raimondo.

“The real winner tonight wasn’t anyone at Bama, it was the guy who lives north of Boca. None of the candidates moved support away from the front-runner tonight or any of the prior debates,” said Scott Walker, the Republican former governor of Wisconsin and 2016 presidential candidate, said referring to Mr. Trump.

Alyce McFadden contributed reporting.