Democratic presidential candidates are united in condemning President Donald Trump for seeking a foreign country’s help to trash a domestic political rival. But when it comes to defending the president’s target, former Vice President Joe Biden, it’s more complicated.

Massachusetts Sen. Elizabeth Warren suggested she’d consider barring her vice president’s children from serving on the boards of foreign companies, the very kind of business arrangement Trump has used in unfounded attacks accusing Biden and his son Hunter of corruption.

When asked whether Trump’s attacks reflect on Biden’s “campaign or his character,” California Sen. Kamala Harris said, “I’ll leave that up to the pundits. I don’t have a comment on that.” And Vermont Sen. Bernie Sanders, who in 2016 defended Hillary Clinton against attacks over her use of a private email server as secretary of state, sidestepped a question about whether the Biden controversy makes him a weaker candidate.

The reactions signal just how contentious the Democratic primary could become in the months ahead if it unfolds against the backdrop of impeachment proceedings in Congress. Even as Biden’s leading competitors for the Democratic presidential nomination accuse Trump of abusing the power of his office, they have been willing to let Biden navigate the situation on his own.

Without evidence, Trump and his Republican allies continue to suggest that Biden, while vice president, tried to quash a Ukrainian investigation of the company that paid Hunter Biden as a board member. As Trump’s private attorney Rudy Giuliani pushed the nefarious Biden theories, the top Ukrainian prosecutor said earlier this year that his team found no wrongdoing, and there’s no evidence that U.S. law enforcement has gotten involved.

Trump, nonetheless, raised his theory in a July telephone conversation with the new Ukrainian president, asking Volodymyr Zelenskiy to investigate the Bidens anew. That move, now the center of a formal whistleblower complaint and a House impeachment inquiry, could be found to violate U.S. law making it a crime to solicit or accept foreign contributions in an American election.

It fell to candidates largely outside the top tier to offer strong defenses of Biden.

Mayor Pete Buttigieg of South Bend, Indiana, on CNN rejected questions about Biden, calling that “whataboutism” that allows Republicans to avoid scrutiny on “an extraordinary, perhaps unprecedented, breach of the oath of office by the American president.”

When Trump tweeted this week that he expected “transparency” from the Bidens, New Jersey Sen. Cory Booker answered him: “Well, we found one thing that’s transparent: your deception. We’re not going to let you do this again to another patriot.”

Even former U.S. Housing Secretary Julian Castro, who memorably attacked Biden during a Sept. 12 debate by falsely accusing the 76-year-old of forgetting his own health care proposals, weighed in on Biden’s behalf. “Donald Trump is trying to do to Joe Biden what he did to Hillary Clinton, to turn somebody who has given a lifetime of service and done it honorably into the victim of false accusations,” Castro told reporters.

The disparity has frustrated Biden and his allies. Biden advisers say they will aggressively push back at Trump’s characterizations, remembering that in 2016, Trump was often successful in framing his opponents however he pleased: “Lyin’ Ted” Cruz, “Low energy Jeb” Bush and “Little Marco” Rubio in the GOP primary, “Crooked Hillary” Clinton in the general election campaign.

In the Ukraine storyline, they see Trump as trying to project his potential weaknesses — his foreign business entanglements — onto Biden, as he did in 2016 with persistent attacks on the Clinton Foundation and its international fundraising activities when Clinton was secretary of state. But the Biden team wants help from other Democrats, believing the party should close ranks against Trump’s unsupported allegations against any candidate.

“You’ve got to put the national interest ahead of your own personal interest in the primary,” said Sen. Chris Coons, a Delaware Democrat and top Biden supporter. Besides, Coons warned, even a purely political calculation should have Biden rivals coming to his defense, lest they find themselves in Trump’s line of fire.

“He’s going to keep smearing whoever is the leading Democratic presidential candidate,” Coons said. “Joe Biden is the leading candidate now, so that’s why he’s starting with Joe Biden. But it’s going to be spread around. And they should recognize that this is a threat not just to their electoral prospects but to our democratic process.”

For his part, Biden isn’t changing his campaign script. From the beginning, he’s centered his candidacy on the idea that Trump is a uniquely existential threat to the nation’s identity — a contention that has grown in the wake of this week’s revelations.

“We’ve never seen his likes before holding public office,” Biden told donors Thursday at a fundraiser outside Los Angeles, where he read portions of the whistleblower report made public earlier in the day.

“This isn’t about me,” Biden said. “It’s a tactic that’s used by this president to try to hijack an election, so we do not focus on the issues that matter in our lives.”

(AP)