Democratic presidential candidates are pushing back on former Housing and Urban Development Secretary Julián Castro after a fiery exchange he had with former Vice President Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE during Thursday's primary debate in Houston.

During Thursday's debate, the two men sparred over Biden's health care plan and Castro accused the former vice president of forgetting comments he made just minutes earlier.

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"Are you forgetting what you said two minutes ago?" Castro fired at Biden on the issue of auto-enrollment in health care plans. "Are you forgetting what you said two minutes ago? I can't believe that you said, two minutes ago, that they had to buy in and now you're forgetting that. We need a health care system where you're automatically enrolled."

Castro later said he was not taking a shot at Biden's age, but was just focusing on his comments from moments earlier.

South Bend, Ind., Mayor Pete Buttigieg Pete ButtigiegBillionaire who donated to Trump in 2016 donates to Biden The Hill's Morning Report - Sponsored by Facebook - GOP closes ranks to fill SCOTUS vacancy by November Buttigieg stands in as Pence for Harris's debate practice MORE (D) took aim at Castro onstage after the remarks, saying that the comments were why debates were "becoming unwatchable."

"That's called the Democratic primary election, Pete. That's called an election," Castro shot back, to some laughs.

Several candidates pushed back on Castro's comments in the spin room, with some saying the former secretary's rhetoric onstage had verged on Trumpian, according to CNN.

"It feels like something that Donald Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE might tweet," Sen. Amy Klobuchar Amy Klobuchar3 reasons why Biden is misreading the politics of court packing Social media platforms put muscle into National Voter Registration Day Battle lines drawn on precedent in Supreme Court fight MORE (D-Minn.) told CNN, adding that the attack was "so personal and so unnecessary."

Sen. Cory Booker Cory Anthony BookerThe movement to reform animal agriculture has reached a tipping point Watchdog confirms State Dept. canceled award for journalist who criticized Trump 3 reasons why Biden is misreading the politics of court packing MORE (D-N.J.) defended Castro's comments after the debate, saying the concerns were "legitimate."

"I've seen this movie before in the last election," Booker said.

"But you saw the way I did it. It wasn't a cheap shot," he added of his own past onstage clashes with the former vice president.

Booker added to his comments on CNN's "New Day" Friday morning, explaining that he finds concerns about Biden "fumbling" onstage to be "really important," but saying that he took issue with how the issue was raised.

"We love our country, and we want to have the best candidate for that. What I do have a problem with is tone, tenor, how we go at each other," Booker said.

"I saw this last election, how we tore candidates down, how we tore individuals down, in such a way that after the primary we didn't have the kind of unity that we need," he added.

Sen. Cory Booker: “The challenge for Democrats right now is not to just beat Republicans, it’s to unite Americans in a larger sense of common cause and common purpose… I think I’m the best person to be on the field to get that done.” https://t.co/Mo7ThGB9Sw pic.twitter.com/ElD9NfOhQI — New Day (@NewDay) September 13, 2019

Former Rep. Beto O'Rourke Beto O'RourkeJimmy Carter says his son smoked pot with Willie Nelson on White House roof O'Rourke endorses Kennedy for Senate: 'A champion for the values we're most proud of' 2020 Democrats do convention Zoom call MORE (D-Texas) was more direct in his criticism of Castro, telling CNN that the remarks would not help Democrats in in 2020.

"That will not defeat Donald Trump. That won’t bring this deeply divided country back together again," the former congressman said. "That kind of personal attack I don’t think is what we need right now and is insufficient to the challenges we face."

Beto O’Rourke on Julián Castro’s jab at Joe Biden’s memory: "That will not defeat Donald Trump. That won’t bring this deeply divided country back together again … That kind of personal attack I don’t think is what we need right now and is insufficient to the challenges we face” pic.twitter.com/EoCA5SIyBG — CNN Politics (@CNNPolitics) September 13, 2019

Sen. Kamala Harris Kamala HarrisTexas Democratic official urges Biden to visit state: 'I thought he had his own plane' The Hill's Campaign Report: Biden on Trump: 'He'll leave' l GOP laywers brush off Trump's election remarks l Obama's endorsements A game theorist's advice to President Trump on filling the Supreme Court seat MORE (D-Calif.) was more measured in her remarks when asked about Castro, explaining that “it’s a debate stage — things get heated.”

"But I do believe that...the focus needs to be on the fact that Donald Trump is not doing the American people the benefit of the office," Harris told CNN on Friday.

"It's a debate stage. Things get heated," Kamala Harris says on Julián Castro's attack on Joe Biden in last night's #DemDebate, adding that "the focus needs to be on the fact that Donald Trump is not doing the American people the benefit of the office" https://t.co/XZiMZ6VBEd pic.twitter.com/JORJWsO7Rp — CNN Politics (@CNNPolitics) September 13, 2019

During his own spin room interview after the debate, Castro added that his remark aimed at Buttigieg was not meant as a personal slight.

"This is a debate. And when we're talking about health care policy, we're talking about a policy that impacts every single person in this country," Castro told CNN.

—Updated at 10:45 a.m.