Sen. Tammy Duckworth, an Illinois Democrat and veteran of combat missions in Iraq, said she had concerns about Tulsi Gabbard, Trump’s choice to be director of national intelligence.

“I think she’s compromised,” Duckworth said on CNN’s “State of the Union,” citing Gabbard’s 2017 trip to Syria, where she held talks with Syrian President Bashar Assad. Gabbard was a Democratic House member from Hawaii at the time.

“The U.S. intelligence community has identified her as having troubling relationships with America’s foes. And so my worry is that she couldn’t pass a background check,” Duckworth said.

Gabbard, who said last month she is joining the Republican Party, has served in the Army National Guard for more than two decades. She was deployed to Iraq and Kuwait and, according to the Hawaii National Guard, received a Combat Medical Badge in 2005 for “participation in combat operations under enemy hostile fire in support of Operation Iraqi Freedom III.”

Duckworth’s comments drew immediate backlash from Republicans.

“For her to say ridiculous and outright dangerous words like that is wrong,” Sen. Markwayne Mullin, a Republican from Oklahoma, said on CNN, challenging Duckworth to retract her words. “That’s the most dangerous thing she could say — is that a United States lieutenant colonel in the United States Army is compromised and is an asset of Russia.”

In recent days, other Democrats have accused Gabbard without evidence of being a “Russian asset.” Sen. Elizabeth Warren, a Massachusetts Democrat, has claimed, without offering details, that Gabbard is in Russian President Vladimir “Putin’s pocket.”

Mullin and others say the criticism from Democrats is rooted in the fact that Gabbard left their party and has become a Trump ally. Democrats say they worry that Gabbard’s selection as national intelligence chief endangers ties with allies and gives Russia a win.

Rep. Adam Schiff, a California Democrat just elected to the Senate, said he would not describe Gabbard as a Russian asset, but said she had “very questionable judgment.”

“The problem is if our foreign allies don’t trust the head of our intelligence agencies, they’ll stop sharing information with us,” Schiff said on NBC’s “Meet the Press.”

Gabbard in 2022 endorsed one of Russia’s justifications for invading Ukraine: the existence of dozens of U.S.-funded biolabs working on some of the world’s nastiest pathogens. The labs are part of an international effort to control outbreaks and stop bioweapons, but Moscow claimed Ukraine was using them to create deadly bioweapons. Gabbard said she just voiced concerns about protecting the labs.

Gabbard also has suggested that Russia had legitimate security concerns in deciding to invade Ukraine, given its desire to join NATO.

Republican Sen. Eric Schmitt of Missouri said he thought it was “totally ridiculous” that Gabbard was being cast as a Russian asset for having different political views.

“It’s insulting. It’s a slur, quite frankly. There’s no evidence that she’s a asset of another country,” he said on NBC.

Sen. James Lankford, another Oklahoma Republican, acknowledged having “lots of questions” for Gabbard as the Senate considers her nomination to lead the intelligence services. Lankford said on NBC that he wants to ask Gabbard about her meeting with Assad and some of her past comments about Russia.

“We want to know what the purpose was and what the direction for that was. As a member of Congress, we want to get a chance to talk about past comments that she’s made and get them into full context,” Lankford said.