WASHINGTON — As the first Black woman elected to the U.S. House from Pennsylvania, U.S. Rep. Summer Lee (PA-12, including most of Pittsburgh) is traveling a different path than her predecessors.

The freshman lawmaker this year quickly allied herself with a group of young, liberal lawmakers known as the Squad, including Reps. Alexandria Ocasio-Cortez of New York, Ilhan Omar of Minnesota, and Rashida Tlaib of Michigan. The lawmakers, all people of color, seek to push the House Democratic caucus further to the left.

Ms. Lee’s predecessor, 14-term Democrat Mike Doyle, was considered more moderate. While she is a member of the Congressional Progressive Caucus, Mr. Doyle, who retired after 2022, was not. Mr. Doyle even endorsed one of Ms. Lee’s primary opponents, Steve Irwin. And Mr. Doyle ranked 98th of 435 House members in a 2021 index of bipartisanship from Georgetown University and the Lugar Center, a public policy group founded by the late U.S. Sen. Richard Lugar, R-Ind. (Ms. Ocasio-Cortez ranked 401st.)

“Anytime you can add a new perspective to the Congress, especially someone who has had unique experiences in this country, it is beneficial,” said U.S. Rep. Donald Payne, D-N.J., one of Ms. Lee’s fellow members of the Congressional Black Caucus. “Ms. Lee has demonstrated her leadership already and I’ve been very impressed with her. She took the place of a great member. Everybody was watching to see how she would perform and she’s getting her legs under her and learning very well the ways of the House of Representatives.”