FORT LAUDERDALE, Fla. — Republican senators on Sunday pushed back against criticism from Democrats that former Rep. Tulsi Gabbard, President-elect Donald Trump’s pick to lead U.S. intelligence services, is “compromised” by her comments supportive of Russia and secret meetings, as a congresswoman, with Syria’s president, an ally of the Kremlin and Iran.

Sen. Tammy Duckworth, D-Illinois, a veteran of combat missions in Iraq, said she had concerns about Gabbard, the pick for 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 representative 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 over two decades. She served in Iraq and Kuwait.

Duckworth’s comments drew immediate backlash from Republicans.

“For her to say ridiculous and outright dangerous words like that is wrong,” Sen. Markwayne Mullin, R-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.” 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.

Sen. James Lankford, another Oklahoma Republican, said he has “lots of questions” for Gabbard as the Senate considers her nomination. He said on NBC that he wants to ask her about her Assad meeting and comments about Russia.