Democrat candidates for president on Tuesday face a tough decision in the presidential primary debate, as former Vice President Joe Biden faces additional scrutiny.

While he was vice president, Biden failed to stop his son Hunter Biden from cashing in on lucrative foreign business deals with Ukraine and China even as he was leading the Obama administration’s diplomatic efforts with the two countries.

President Donald Trump made it a focal point of his campaign, using Hunter Biden’s name in back-to-back rallies last week, ultimately forcing Hunter Biden to step down from his role in an investment company backed by China on Sunday.

Hunter Biden’s lawyers, however, were unclear whether he would keep his stake in the company — estimated at an investment worth millions.

But 2020 candidates are hesitant to swing at Biden, and some even appear defensive of the vice president on the issue of corruption.

The Biden campaign also fired a warning to his campaign rallies.

An aide to Biden told Bloomberg News any candidate who “calls themselves a ‘Democrat'” and repeats what the aide said were “discredited lies” about Biden and his son “would be making a profound statement about themselves.”

Sen. Warren at first stumbled by suggesting she did not approve of the idea of a vice president allowing to serve on the board of a foreign company.

“No. … I don’t know. I mean, I’d have to go back and look at the details,” she replied.

Since then, Warren dodged media attempts to answer questions about Biden and his son, pivoting back to accuse Trump of trying to dodge his own misconduct in Ukraine.

Sen. Bernie Sanders has also dodged the question, demanding “evidence” of any impropriety by the Bidens.

“I know I’m a little bit old-fashioned. I like to see the evidence before I talk about things. I read the papers and I read what I read,” Sanders said last week. “But I don’t know that I know enough at this point to make any definitive statement.”

Sen. Kamala Harris has also defended Biden, pointing instead at Trump.

“Mr. President, telling lies about Joe Biden won’t protect you from the truth. Joe has more patriotism in his pinky finger than you’ll ever have,” Harris wrote on Twitter.

Harris scored an early hit on Biden by questioning his history of opposing public bussing in public schools, even earning a bump in the polls, but the early momentum soon faded.

Attacking Biden has not worked well for other candidates as well. Former Housing Secretary Julian Castro swung at Biden, questioning memory loss in the last debate, but missed, earning scorn from pundits and Democrat voters.

Sen. Kirsten Gillibrand tried to score points against Biden on women’s issues, but her attack came off as self-serving, leading her to ultimately drop out of the race.

Other low-polling candidates who tried to score points against Joe Biden, such as New York City Mayor Bill DeBlasio and Rep. Eric Swalwell, soon dropped out of the race after their attacks failed to resonate with primary voters.

Castro did not appear interested in hitting the Bidens again, responding to questions about Hunter Biden by criticizing Trump.

“Donald Trump is trying to use the same playbook against Joe Biden as he used against Hillary Clinton,” he said.

Mayor Pete Buttigeig began the week by vocally defending Biden on CNN, earning praise from the former Vice President.

“I’m a friend of Pete Buttigieg,” Biden told the United Food and Commercial Workers 2020 presidential forum on Sunday. “By the way, he’s a really decent guy. I turned on the television this morning and he was defending me and my family against these outrageous, lying ads of the president of the United States of America. That’s a good man.”

Sen. Cory Booker, who at times cannot resist taking gratuitous shots at Biden, has also stood up for the president.

“This is unacceptable, that if you come after Joe Biden, you’re going to have to deal with me in this case, these are baseless, unfounded, scurrilous lies,” he said in October.

But in September, Booker also questioned Hunter Biden’s actions when Trump’s attacks took form.

“I just don’t think children of vice presidents, presidents during the administration should be out there doing that,” he said.

Other candidates have promised not to allow similar behavior if they were elected president.

“I would not allow a family member, anyone in my cabinet to have a family member, to work in a position like that,” Rep. Beto O’Rourke said

Sen. Amy Klobachar promised the same.

“I can promise you right now, my own daughter, who’s only 24, does not sit on the board of a foreign company,” she said on CNN.

Andrew Yang said Hunter Biden’s role in foreign companies “certainly has a bad look to it.”

“In my mind they can wait until the term is over before serving that term,” he said. “And that’s really the way it would be under my administration.”

Tulsi Gabbard remains the wildcard.

After a devastating series of attacks against Sen. Kamala Harris in the August debate, Gabbard demonstrated she knew how to criticize the substance of her opponent’s record, without sounding gratuitous.

When asked to weigh in on the Biden’s she said that allowing a vice president’s son to sit on a corporate board “would be a poor decision to make.”

“I don’t know what went into that or how he got hired or why or what influence there was used, if any, but I think the perception is certainly a concern,” she said.