By Eric Bradner, CNN

(CNN) -- President-elect Joe Biden and Vice President-elect Kamala Harris are set to hold a virtual meeting with leaders of civil rights organizations Tuesday in Wilmington, Delaware, as Biden faces pressure to appoint a diverse slate of nominees to Cabinet positions and top administration posts.

The meeting comes as Biden seeks to fulfill his pledge to select a Cabinet that looks like America amid complaints from some leaders of Black, Latino and Asian American groups that he has not moved swiftly enough to do so.

Last week, Biden promised a Cabinet with "significant diversity" after hearing frustrations from the NAACP and other civil rights groups that Biden had not selected Black nominees to lead the State and Treasury departments.

"I'm not going to tell you now exactly what I'm doing in any department, but I promise you, it'll be the single most diverse cabinet, based on race, color, based on gender, that's ever existed in the United States of America," Biden told reporters Friday.

Since then, Biden chose retired Army Gen. Lloyd Austin, the former commander of US Central Command, to be his secretary of defense. And he tapped California Attorney General Xavier Beccera to lead the Department of Health and Human Services, after the Congressional Hispanic Caucus voiced frustrations over his team's handling of another candidate, New Mexico Gov. Michelle Lujan Grisham, for the post.

On Monday, more than 1,000 influential Black women signed a letter urging Biden and Harris to consider and appoint more Black women to hold Cabinet positions. The letter singled out potential candidates, including some who have been reported to be under consideration for Cabinet posts: Ohio Rep. Marcia Fudge to lead the Department of Agriculture and Atlanta Mayor Keisha Lance-Bottoms to helm the Department of Housing and Urban Development.

"Just as Black women and Black Americans were key to your election in November, we are key to the success of your Administration and the implementation of your vision. Our community must see ourselves reflected in key leadership positions in recognition of our importance," the letter said.

Leaders of the seven groups meeting with Biden are set to hold a news conference Tuesday evening after the private meeting.