(Reuters) – The U.S. Senate on Thursday voted to confirm a federal judge who is a protege of Senate Republican Leader Mitch McConnell to an influential appeals court in Washington. Justin Walker, 38, won Senate approval to the U.S. Court of Appeals for the District of Columbia Circuit following a mostly party-line 51-42 vote. Senator Susan Collins of Maine was the only Republican joining Democrats in voting against confirming the appointee of President Donald Trump. Walker is being elevated from the U.S. District Court in Louisville, Kentucky, where he has been a judge since October. Walker, a former academic, is close to McConnell. He was also a vocal ally of Supreme Court Justice Brett Kavanaugh during his confirmation battle in the Senate in 2018. Several Democratic lawmakers said during a May 6 confirmation hearing that Walker was too inexperienced for the job. The D.C. Circuit is considered the second most powerful court in the country, in part because it handles many high-stakes challenges to federal regulations. Four of the current nine justices on the Supreme Court were previously D.C. Circuit judges. Although based in Kentucky, where he has taught at the University of Louisville’s law school, Walker has Washington ties. He clerked for Kavanaugh on the D.C. Circuit, where Kavanaugh served for 12 years. He also clerked for Supreme Court Justice Anthony Kennedy, who Kavanaugh replaced in 2018. After Trump, a Republican, nominated Kavanaugh to the Supreme Court, Walker frequently appeared on cable TV, including Fox News, talking up the nominee’s conservative credentials. Walker defended his qualifications during last month’s hearing, saying “there is a long and rich tradition of academics being nominated” to federal appellate courts. “We Kentuckians are sorry to lose Judge Justin Walker, but we’re very proud this brilliant and fair jurist will be serving our nation on the D.C. Circuit,” McConnell wrote on Twitter on Thursday.