U.S. Rep. John Yarmuth on Monday endorsed Morgan McGarvey as his choice to succeed him, touting the state lawmaker's progressive credentials as Democrats seek to retain their lone seat in Kentucky's congressional delegation.The endorsement from the popular Yarmuth — who routinely coasted to reelection — figures to be a big boost for McGarvey in his two-way primary-election contest in the Louisville-area 3rd District.McGarvey is the top-ranking Democrat in the Republican-dominated Kentucky Senate. He's built solid ties with his party's establishment and has amassed a huge fundraising advantage over his primary rival, state Rep. Attica Scott.Louisville — the state's largest city — remains a Democratic stronghold while most of Kentucky is solidly Republican. Several Republicans are running for the 3rd District seat, which Yarmuth gained by ousting a veteran GOP congresswoman in 2006.Going into retirement: U.S. Rep. John Yarmuth, Democrat representing much of Louisville, won't seek reelectionAt their joint appearance Monday, Yarmuth described McGarvey as a "true champion of progressive values." He said McGarvey has shown an ability to help build coalitions "necessary to create meaningful change."Yarmuth, the influential chairman of the House Budget Committee, announced last fall that he wouldn't run another term as he seeks to spend more time with his family. Yarmuth played a role in passing high-profile national measures, including pandemic-relief legislation and the bipartisan infrastructure bill.The congressman acknowledged Monday it will be a "bittersweet moment" when he leaves office."But I'll be reassured to know that this seat is in Morgan's capable hands," Yarmuth said. "And I assure you that I would be proud to call him my representative in Congress."McGarvey said that as a state legislator he's tried to follow Yarmuth's example. He praised Yarmuth for having "stayed true to his values" while building coalitions to "get big things done.""I'm running for Congress in part to make sure that Louisville continues to have an effective voice in Washington," McGarvey said. "There's problems that we see every day. Those problems deserve a federal response."Another lawmaker running: Kentucky Rep. Attica Scott announces congressional run against U.S. Rep. John YarmuthHe praised Yarmuth's steadfast support for the Obama-era Affordable Care Act, which he said enabled more than 400,000 additional Kentuckians to gain access to health insurance coverage.McGarvey endorsed a series of progressive policies — universal prekindergarten, the child tax credit program, paid family leave and efforts to combat climate change, including more green jobs as part of an overall jobs-growth plan.Scott's campaign didn't immediately respond to an email seeking comment on Yarmuth's support for her primary opponent. Scott, who is Black, entered the campaign before Yarmuth announced his pending retirement. McGarvey, who is white, joined the campaign immediately after the incumbent's announcement. Scott promotes a platform of economic and racial justice issues.Under the GOP's new redistricting plan for Kentucky, the 3rd District remained basically intact, covering most of Jefferson County, which includes Louisville. Whites make up nearly 64% of Louisville's population, while Blacks account for more than one-fifth of the city's population, according to census figures.Yarmuth on Monday acknowledged his long-running policy of not making endorsements in non-presidential primaries. He said he concluded it was his responsibility -- based on the perspective he gained during his years in Congress — to publicly weigh in on his preference for a successor.Kentucky's primary election is set for May 17. But the state's newly redrawn congressional districts, passed last month by the legislature, have drawn a court challenge.