Katherine Porter, center, testifies before the congressional oversight panel for the Troubled Asset Relief Program on Oct. 27. (Mandel Ngan/AFP/Getty Images)

Emily’s List, the progressive organization that boosts female Democrats who support abortion rights, has issued its earliest-ever in-cycle candidate endorsement, throwing support behind Irvine, Calif., law professor Katie Porter in her race against Rep. Mimi Walters (R-Calif.).

The endorsement is a boost for Porter, a first-time candidate who studied under Sen. Elizabeth Warren (D-Mass.) at Harvard Law School and who has been endorsed by the Massachusetts senator and by Sen. Kamala D. Harris (D-Calif.). It’s also one of the first attempts by a progressive group to provide clarity in the increasingly busy primaries taking place in swing seats, as renewed liberal activism has led to a surge of new candidacies.

“I think Emily’s List will send a strong signal that the eyes of this nation are on this race,” Porter said in an interview. “It’s been very, very supportive throughout the process of starting a campaign. This endorsement is a proof point of the quality of the campaign we’re running.”

It’s also an attempt at solving what has become a slow-burning problem for Democrats — the glut of ambitious candidates seeking offices that the party has struggled to win. Walters was elected in 2014 to fill a traditionally safe Republican seat based in Orange County, taking 65 percent of the vote that year and 60 percent in 2016. That year, the Democrats fielded a token candidate who spent less than $45,000 on his race, and raised even less.

But Hillary Clinton carried the increasingly diverse and highly educated district by five points, leading to a 2018 candidate surge. Porter is one of three Democrats fighting for a runoff slot against Walters, joining David Min, a former staffer for Senate Minority Leader Charles Schumer (D-N.Y.), and Kia Hamadanchy, a former staffer for Sen. Sherrod Brown (D-Ohio).

Porter, an expert in foreclosure who had expected to work on policy in a Hillary Clinton administration — she had packed a suitcase for Washington, unpacking it after the results came in — is attempting to break through.

To win the House for the first time since 2008, Democrats believe they must take all six Republican-held California districts where Clinton defeated Trump. Since the introduction of the two-step primary, California Democrats have sometimes blown opportunities for gains when a crowded field split their vote, allowing two Republicans into a runoff. That’s less likely in Walters’s district — there is no credible Republican challenge — but it’s factored into progressive strategizing about the midterms.