Two outside groups supportive of Hillary Clinton’s campaign are running their first ads as part of a multimillion dollar advertising effort hoping to energize the millennial female voting base.

Priorities USA, the “super PAC” supporting Hillary Clinton, and Emily’s List, the political action committee that works to elect Democratic women, have partnered on the campaign, which they said will run through the general election. They are expected to spend roughly $20 million on the effort.

The first element of this campaign will be a $500,000 digital ad buy, in partnership with the American Federation of Teachers, which will run in early states with a focus on Texas, Virginia, Michigan, Illinois, Florida, North Carolina and Ohio.

“Right now, young women are some of the most dedicated and active progressives this country has ever seen,” Denise Feriozzi, the deputy executive director of Emily’s list, said in a statement. “And we have the candidate to match this moment.”

Titled “Give ‘Em Hill,” the campaign will cite Mrs. Clinton’s record and her fight for equal pay for women. The content revolves around a website and two 15-second pre-roll ads that will run on YouTube, Facebook, Instagram and elsewhere online, with a casual style tailored for the millennial audience.

“When you find out that bro who has your same job gets paid more than you,” a woman says in the ad, “you give ’em Hill,” before a Vote for Hillary on March 1 title card closes the ad.

The effort comes as Mrs. Clinton has struggled to connect with younger voters, who have flocked to Senator Bernie Sanders’s campaign. In New Hampshire, 79 percent of women under 30 voted for Mr. Sanders over Mrs. Clinton, according to exit poll data.