The US Senate confirmed Tulsi Gabbard on Wednesday to serve as Director of National Intelligence (DNI).
President Donald Trump's pick was confirmed in a 52-48 vote.
Mitch McConnell was the only Republican senator to vote against Gabbard.
During her confirmation hearing last month, Gabbard vowed to do her "very best" to find the truth, share it with Trump, his advisors and provide Congress with "unbiased, timely, and accurate" intelligence.
Gabbard, a 43-year-old former Democrat, faced criticism about her lack of experience and questionable judgment.
She faced questions about past statements seen as sympathetic toward Russia's war in Ukraine.
Her controversial 2017 meeting with then-Syrian leader Bashar al-Assad also sparked outrage.
Senate Minority Leader Chuck Schumer urged senators to think twice about her confirmation.
"It's a person who has said things like, the Ukraine invasion was caused by the United States, not by (Russian President Vladimir) Putin. It's somebody who has denied Assad's use of chemical weapons despite all of the intelligence," he said on the Senate floor before the vote.
Gabbard's nomination endangers the security of the US, said Schumer. "My guess is, if a secret ballot were cast on Tulsi Gabbard, maybe she'd get 10 votes. You all know how bad she is," he added.
