WASHINGTON – Some 2020 Democratic presidential candidates that took aim at former President Barack Obama during this week's primary debates are now trying to walk back their criticisms.

"Heck, if [Obama] was running for president for a third term, I wouldn't be running," Sen. Cory Booker of New Jersey told CNN on Thursday.

Some of Obama's policies were discussed during Wednesday night's debate, including his trademark health care legislation, the Affordable Care Act -- or the eponymous "Obamacare." Several Democratic 2020 hopefuls criticized Obamacare and have called for a more comprehensive approach to providing health insurance coverage through policies like Medicare for All. Former Vice President Joe Biden, however, said he would protect and build on the ACA.

In a tweet Friday, Biden pushed back on the implication that Obama had not been bold enough in dealing with health care policy when the former president worked to have Obamacare passed. "There is nothing moderate about what President Obama did with Obamacare. Nothing," Biden tweeted. "Seven presidents tried to expand access to health care — the Obama-Biden Administration finally got it done."

Obama is rated as the best president by Americans during their lifetimes, according to a 2018 report from Pew Research Center.

And after Wednesday's debate, some political observers puzzled over the criticism of Obama's policies by his fellow Democrats. "When did Barack Obama become a Republican?," John Avlon asked in an op-ed for CNN.com that went on to defend Obama and his policies and to caution against the current climate of overheated political rhetoric in both parties.

And Washington Post opinion writer Stephen Stromberg argued that the attacks on Obama's policies could serve the interests of President Donald Trump because they "provide talking points for a president determined to denigrate his predecessor and to diminish his legacy by any means possible."

Sen. Kamala Harris, D-Calif., on Thursday said she had "nothing but praise for President Obama."

"I think he did great work,” she told reporters Thursday. “We talked about the health care system. Many presidents before him tried to reform America’s health care system. He actually got it done.”

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During Wednesday night's debate, Harris was taken to task for her newly released health care plan, which would transition to a Medicare for All system over 10 years. During the transition, the role for private insurers would be preserved.

Sen. Cory Booker during Wednesday night's debate slammed Biden for invoking Obama, saying: "You can’t have it both ways. You invoke President Obama more than anyone in this campaign. You can’t do it when it’s convenient and then duck it when it’s not.”

On Thursday, Booker maintained that although Obama is the Democrat's "statesman," he is not immune from criticism.

"He is our statesman," Booker said of Obama. "He ain't perfect. Nobody's ever pulled that off. Nobody has ever pulled that off."

"I'm sure if Barack Obama was sitting here — and I hope he's sleeping this morning — he would tell you, 'I've made some mistakes,'" Booker continued.

The Obama administration's immigration record was also called out for criticism during Wednesday's debate.

Julián Castro, who was Housing and Urban Development secretary under Obama, called into question the high number of deportations that occurred under Obama's watch.

Biden told Castro during the debate that he hadn't heard that complaint from him at the time when they both worked for Obama.

"One of us has learned the lessons of the past and one hasn’t," Castro replied.

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Later in the night, however, Castro thanked Obama for helping revive an economy that was in ire straits in 2009 when Obama took office. In a tweet posted Thursday, Castro highlighted that moment in the debate.

"Donald Trump likes to take credit for the economy, but Americans know President @BarackObama turned our economy around and expanded opportunity for millions. #ThanksObama," Castro wrote in a tweet.

Biden has criticized his fellow 2020 Democrats for going after Obama.

“I must tell you I was a little surprised by how much incoming there was about Barack —about the president,” the former vice president said Thursday. “I’m proud of having served with him. I’m proud of the job he did. I don’t think there is anything he has to apologize for … It kind of surprised me, the degree of the criticism.”

Contributing: Aamer Madhani

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