During a fundraising video call Tuesday, presumptive Democratic presidential nominee Biden attacked Trump for his apparent failings on foreign policy and his handling of the COVID-19 coronavirus pandemic, cases and deaths from which are accelerating rapidly across the U.S.

Biden—who is leading Trump in opinion polls nationwide, including in the swing states that will likely decide the November election—accused Trump of “coddling Putin,” a prominent criticism of the president among his opponents during his time in office.

“Putin carries him around like a puppy in one of those little puppy cages,” Biden said, according to a pool report sent out by the former vice president’s campaign team.

Russia and Putin have loomed over Trump since the campaign trail, amid allegations of an improper relationship between the New York billionaire and the Kremlin. Since coming into office, the president has had to fight off investigations into pro-Trump Russian meddling in the 2016 presidential election.

He has also been repeatedly accused of pursuing foreign policy beneficial to Moscow while cozying up to Putin in public despite the strongman’s corruption, human rights abuses, and attacks on U.S. allies.

Trump’s Russia problem resurfaced last month when The New York Times reported that Moscow had been offering Taliban fighters in Afghanistan bounties on U.S. troops. The Washington Post said the bounties were linked to multiple American deaths in the country.

The White House has said that Trump was not briefed on the allegations before the Times’ report, but other reports have suggested that the information was included in the president’s security briefings some time before the public revelation.

Russian officials have denied any backing for the Taliban, while White House Kayleigh McEnany has stressed that intelligence officials have not reached a consensus on the validity of the unverified bounty reports.

Biden accused Trump of failing in his presidential responsibilities over the bounties. Last week, he told reporters, “The idea that somehow he didn’t know or isn’t being briefed, it is a dereliction of duty. If that’s the case, and if he was briefed and nothing was done about this, that’s a dereliction of duty.”

Biden also defended potential vice president pick Sen. Tammy Duckworth against attacks by Fox News host Tucker Carlson, who said on his show that the Iraq veteran was “a deeply silly and unimpressive person” and that she and other Democrats “actually hate America.”

Trump retweeted a clip of Carlson’s show and his campaign issued a statement from Scott O’Grady, co-chair of Veterans for Trump, and Patrick Brady, a Medal of Honor recipient, accusing Duckworth of “using her military service to deflect from her support for the left-wing campaign to villainize America’s founding.”

“Folks we cannot let this stand,” Biden said of the Trump campaign’s criticism of Duckworth. “If you had told me this—I had low expectations but, anyway, I shouldn’t get going,” he said on the Tuesday call which Duckworth also attended.