Mr. Schiff and Ms. Porter, for their part, acknowledged the importance of issues of race and gender in the Senate race, though they said how much they factored into the result would ultimately be up to voters. The two also have also sought to draw sharp contrasts between their candidacies.
On a chilly, overcast Saturday, Mr. Schiff, a former prosecutor who led Mr. Trump’s first impeachment trial, billed himself as a staunch defender of democracy and a progressive leader committed to creating jobs and tackling climate and gun safety issues. In Congress, he said, he had dedicated himself to becoming an expert on national security issues, exposing torture and working to overhaul the nation’s surveillance system.
“I took on these fights because they mattered, because they made Americans’ lives better, our system more just, our kids’ future more secure,” he said before some 600 supporters at the union hall parking lot in Burbank, where he launched his first run for Congress more than two decades ago. “And then I took on the biggest fight of my life against Donald J. Trump.”
At a parks and recreation center in Huntington Park, where Ms. Porter met with Latino environmental justice activists and community leaders on Friday, the congresswoman described herself as a political newcomer and a single mother who had never taken corporate PAC money and who would be willing to challenge both parties on issues like child care and paid family leave.
Ms. Porter, who studied under Elizabeth Warren at Harvard, garnered national prominence as she grilled corporate executives and government officials in congressional hearings, often turning to a handy whiteboard to explain complex topics. She pointed to her victories in a competitive swing district as evidence that she could win without compromising her progressive values.
“I have had three really hard races and have won every one of them,” she said in an interview.
Karina Macias, a Huntington Park council member who had taken a walk through the neighborhood with Ms. Porter that morning, said she had not made an endorsement in the race.
“Obviously, diversity is important, being a Latina woman myself,” she said. “For me, it is that, but also who is coming to talk to these cities that have been screaming for years to get some attention from Congress to make sure that we get that discussion on our issues.”
Reid J. Epstein contributed reporting from Washington, D.C.