WASHINGTON — President Joe Biden received widespread praise from Democrats for his fiery State of the Union speech Thursday night, when he leaned in on issues that will likely be central to the 2024 election. But one of the moments that struck a discordant note with some of his allies was on the issue of immigration, when Biden referred to an undocumented immigrant as “an illegal.”

The unscripted moment came when Biden brought up Laken Riley, a 22-year-old nursing student who was murdered in Georgia. An undocumented immigrant has been charged with her killing. Biden called her “an innocent young woman who was killed by an illegal.”

That term has long been rejected and seen as dehumanizing by the Democratic Party and immigration advocates, so it was noticeable when the president used it in a most high-profile speech.

“There was a lot of good in President Biden’s speech tonight, but his rhetoric about immigrants was incendiary and wrong,” Rep. Joaquin Castro, D-Texas, posted to X in the moments after the speech.

Castro’s guest to the annual speech was Priscilla Martinez, the widow of Aaron Martinez, the Texas rancher who was killed by a neighbor in what Castro described as a “hate crime” as a result of anti-Latino hate.

Those charges were ultimately never brought against the man charged with fatally shooting the 35-year-old, but by inviting Martinez, Castro said he aimed to highlight a rise in violence against Hispanic Americans and immigrants in the aftermath of Donald Trump’s presidency.

“The speech was very strong overall, but the President needs to be careful about not adding fuel to the right-wing fire that fearmongers about immigrants and scapegoats them for our national challenges,” Castro added in a statement to NBC News.

Sen. Alex Padilla, D-Calif., who, like Castro, is a member of the Congressional Hispanic Caucus, said “the President’s ad lib last night was deeply disappointing.”

He called the comment “the type of dangerous rhetoric that [Biden] has denounced in the past and I expect that he will do so again. We can not tout a strong economy and nation while at the same time vilifying immigrants who contribute so much to the strength of both.”

But on Friday, Biden appeared to have no regrets, telling reporters, “Well, you know, technically he’s not supposed to be here.”

An aide to a Democratic lawmaker said they were “stunned” by Biden’s use of the phrase, adding that other staffers on Capitol Hill felt similarly as they watched the speech. 

“It was just shocking rhetoric to hear from a Democratic President who campaigned against demonizing immigrants,” they added.

Biden’s comments came after he reversed course on policy in recent months toward the southern border, which has seen record migrant crossings under his administration. Lagging behind in approval ratings and with political pressure to address the crisis growing, Biden declared in January that he would be willing to accept steep restrictions to the asylum system and other measures once inconceivable for many Democrats.

He even went so far as to say he would “shut down the border” if Congress passed legislation that would have given his administration the enforcement mechanism to do so. A bipartisan border bill blocked by Republicans was a topic Biden highlighted during his Thursday night speech.

“That bipartisan bill would hire 1,500 more security agents and officers, 100 more immigration judges to help tackle the backload of 2 million cases. 4,300 more asylum officers and new policy so they can resolve cases in six months instead of six years,” Biden said in the House chamber, directing his ire at Republicans. “What are you against?”

Krish O’Mara Vignarajah, president and CEO of Global Refuge, an immigration advocacy organization, said, “Obviously, language matters, but so does the intent behind it. While it was an unfortunate word choice in a heated moment of heckling in a wider context of this speech, President Biden was quite clear in drawing a stark contrast with the dehumanizing language and policies of his predecessor.”

“I wouldn’t have used the word illegal,” Rep. Robert Garcia, D-Calif., said on MSNBC on Thursday night. “But I think the president quickly shifted, he began quickly talking about immigrants right after that, and I think that as an immigrant myself, I was heartened to talk about the importance of immigrants and to push back on Donald Trump and his rhetoric essentially calling us that we are somehow poisoning the blood of this country.”

Biden campaign manager Julie Chávez Rodríguez told reporters Thursday morning that the president’s policies and actions are what should speak the loudest. 

“Our community knows Joe, they know who is fighting for our community, they know who’s fighting for us,” she said. 

But not all on the left were upset by Biden’s tone during the speech.

Biden brought up Riley holding a button with her name that Rep. Marjorie Taylor Greene, R-Ga., had handed him before the speech. Republicans have invoked her death in their push for stricter border policies — and as a way to blame Biden for not doing enough.

Biden “flipped the script” on Republicans by talking about Riley, one border state Democrat speaking on condition of anonymity said, applauding the way the president “neutralized this issue that Republicans gave him the opening to because they blocked the bill.”

Rep. Ruben Gallego, D-Ariz., who is running for independent Sen. Kyrsten Sinema’s seat, said he thought the speech was “a good reset” for Democrats as they head into a critical election in November where the balance of power in Washington is at stake.

A recent poll showed Latinos have mixed views on immigration. In the Pew Research Center survey, three-quarters of Latinos agreed that the border is in crisis or a problem. However, two-thirds said speeding up asylum decisions with more judges and staff would help and 58% said creating more legal migration pathways was needed. Just a third supported increasing deportations of people in the country illegally, and a quarter backed substantially expanding the wall.

Despite the criticism, Voto Latino, a progressive group focused on mobilizing young Latinos to vote, planned to formally endorse the Biden re-election effort at a rally in Las Vegas that Vice President Harris would be Saturday.

Maria Teresa Kumar, the group’s president and CEO, said that despite Biden’s “forced error” on Thursday, Voto Latino was endorsing him as they realize “young people are struggling with how to participate” in 2024, and they want to show them that “their vote is going to determine the course of our democracy.”

She said those who are hyperfocused on Biden’s language are missing the point, applauding his call for a pathway to citizenship for undocumented immigrants known as Dreamers who arrived in America when they were children.

“I’ve had the privilege of knowing the president for a long time and his words are not what is in his heart,” she said, referring to his “an illegal” remark.

A Mexican immigrant on Friday told NBC News that they were not offended of Biden’s use of the term “illegal.”

“What’s important is to focus on what they’re going to do with migration, not the words that they use,” said Raúl Morales, who added that he is in the process of obtaining his green card and will not be voting in the 2024 election. “Because they can talk using nice words, but if they don’t solve something with migration, it’s not use[ful] to me if they use sophisticated or kind terms.”