The third Republican presidential debate this year, held on Wednesday in Miami, was packed with heated exchanges over abortion policy, immigration and China as the candidates tried to shine as the front-runner, former President Donald J. Trump, once again declined to join them onstage.

This time around, the hopefuls dialed up the battle for second place and delivered digs at President Biden, but directed only glancing criticism at Mr. Trump. There were also plenty of parries between the candidates. At times, they moved beyond policy and became personal, such as when Nikki Haley called Vivek Ramaswamy “scum” after he referred to her daughter.

While Gov. Ron DeSantis of Florida also delivered a nimble performance and made more of an effort to show empathy with voters, commentators tended to agree that Mr. Trump’s strategy of staying away from the debate fray was still paying dividends.

“That debate pretty much seals it for Trump,” Michael McDonald, a professor at the University of Florida who specializes in American elections, said on the social media platform X. “The Munchkins on the stage were too afraid to take him head on.”

Ms. Haley, the former governor of South Carolina who served as ambassador to the United Nations in the Trump administration, had been rising in the polls after two strong debate performances. On Wednesday, despite expectations that she would take some hits, she delivered another steady debate, demonstrating her foreign policy chops in an extended discussion about the war between Israel and Hamas and clapping back at her opponents.

She exchanged barbs with Mr. DeSantis over who was more accommodating of Beijing, despite both taking a firm anti-China stance.

But it was Ms. Haley’s exchange with Mr. Ramaswamy, the entrepreneur who had an early surge in the polls, that will perhaps be the most memorable of the evening. After Mr. Ramaswamy mocked Ms. Haley for pledging to ban TikTok while her adult daughter was a user of the app, Ms. Haley snapped back.

“Leave my daughter out of your voice,” she said. “You’re just scum.”

Ms. Haley also won plaudits for pragmatism on abortion a day after Democrats won big victories in elections across the country because of their strength on the issue. She said that she opposes it but argued that a federal ban was unrealistic given the makeup of Congress. She added that people who support abortion rights should not be criticized.

“Nikki Haley, to her credit, has had nuance and led on the issue from abortion from the outset of her campaign,” Alyssa Farah Griffin, a former director of strategic communications in the Trump administration, said on CNN after the debate.

After two somewhat stilted performances, Mr. DeSantis gave sharp answers on how he would take on China and offer unwavering support for Israel in its fight to dismantle Hamas. He continued to use forceful language about how he would combat the flow of drugs across the southern border and said he would punish universities for allowing antisemitic protests.

Mr. DeSantis also showed a more nuanced side at times, treading carefully when the debate turned to the topic of a federal ban on abortion, defending his opposition to drilling in the Everglades and pledging to make sure people who are eligible receive their full Social Security benefits.

“Tonight was a really strong night for DeSantis, punctuated by a pitch-perfect closing statement,” said Brian Bartlett, a strategist who worked on Mitt Romney’s presidential campaigns in 2008 and 2012. “He not only spoke directly to the issues G.O.P. voters care about, but in a personal and empathetic way that distinguished him from the rest of the pack.”

Following an impassioned second debate, Senator Tim Scott of South Carolina tried to keep the conservative energy flowing with an aggressive approach toward Iran and a staunch position against abortion.

At one point, Mr. Scott even seemed to suggest that the United States should attack Iran.

“You actually have to cut off the head of the snake, and the head of the snake is Iran and not simply the proxies,” he said.

On abortion, Mr. Scott pushed his rivals to support a federal ban on abortions after 15 weeks of pregnancy. The position could play into the hands of Democrats, who have been winning on the issue in elections across the country.

“Voters are practically shouting that what they want is control over their own bodies and not MAGA extremism,” said Alexandra LaManna, a former White House spokeswoman in the Biden administration who focused on reproductive rights.

A former governor of New Jersey, Chris Christie has been the fiercest critic of Mr. Trump, even referring to him as “Donald Duck” for skipping the debates.

On Wednesday, however, Mr. Christie mostly laid off Mr. Trump. Instead, he offered moderate views on abortion, expressed support for raising the retirement age and offered unwavering support for Israel and Ukraine.

In his final statement, Mr. Christie said he was tired of division, anger and petty politics but did not mention Mr. Trump by name.

To some observers, the less pugnacious approach was lacking.

“Christie has entirely faded into the background in this debate,” said James Richardson, a former spokesman and adviser for Gov. Haley Barbour of Mississippi and Jon M. Huntsman, a U.S. ambassador to Russia in the Trump administration. “Highly out of character.”

The debate stage has been less hospitable to Mr. Ramaswamy after he made an early splash on the campaign trail this year. On Wednesday night, he was clearly making every effort to stand out.

Mr. Ramaswamy opened the night by blasting the news media and the NBC debate hosts, and proceeding to lob rapid-fire criticism of all his opponents, except for Mr. Trump.

The attack on Ms. Haley’s daughter succeeded in getting under her skin, but most likely backfired with viewers and voters.

“Nikki expressed what many of us in the audience and at home think of your desperate attempt to create ‘a moment,’” Michael Steele, a former Republican National Committee chairman, said on the X platform.