But they're not taking the day off.
"I certainly admire this as an opportunity to remind people how important women are to our society," said Sen. Jeanne Shaheen, D-New Hampshire. "But I will be here working."
"There's so much mischief going on in this Congress with the Republicans, we dare not turn our backs," quipped Rep. Lois Frankel, a Florida Democrat who chairs the women's caucus in the House.
The same team that organized the Women's March in January encouraged working women to stay home on International Women's Day in a demonstration of economic solidarity they are calling "A Day Without A Woman."
They urged women to take the day off from both paid and unpaid work, wear red and avoid spending money (unless it's on small, women- and minority-owned businesses).
So many women answered the call that schools in Alexandria, Virginia, and Prince George County, Maryland, shut down Wednesday
because more than 300 employees have requested the day off.
The day of protest is the latest evidence that the millions of women who turned out for women's marches around the country the day after President Donald Trump's inauguration are remaining engaged in politics -- particularly as congressional Republicans advance a new measure that would block government dollars from going to Planned Parenthood as part of an Obamacare repeal.
Sen. Claire McCaskill, D-Missouri, said since the Women's March, "a record number" of women are expressing interest in running for public office, and others are "paying very close attention."
"They're trying to make the point that equality is really important because women play such an important role in our economy and our society," McCaskill said. "They're just trying to speak up and say, 'Hey, if we weren't around, you guys would be in a world of hurt.'"
But as for taking the day off, she added: "I'm pretty sure I need to vote."
Female lawmakers' plans
Rep. Barbara Lee, D-California, sent out an email to male and female colleagues in Congress calling for them to participate by wearing red, giving floor speeches about women's issues and coordinating social media activities.
Members of the Congressional Black Caucus are also wearing black flowers "in resistance to President Trump's assault on our communities of color and women of color," Lee said at a rally Wednesday, where close to 50 members of the House, including more than a dozen men, dressed in red and gathered on the east steps of the Capitol.
"We don't want the world to know a day without a woman, but we want people to understand what that day would be like," said House Leader Nancy Pelosi. "And it would not be a day that takes us to our fullest aspiration for the future."
Sen. Kirsten Gillibrand, D-New York, said Tuesday she was planning to wear red but had no plans of staying home. "I want to make sure women's voices are heard in Congress every day," she said.
"I'll be here," said Sen. Patty Murray, D-Washington state. "I applaud everyone who's making their voice heard."
Sen. Debbie Stabenow, D-Michigan, said she would follow Lee's advice and wear red.
Sen. Tammy Duckworth, D-Illinois, said her office is ordering lunch from a woman-owned restaurant that is giving women the day off.
But Duckworth said she won't be taking the day off herself.
"As much as I would like to get out there and show my support by not coming, there's just a lot of work that needs to be done here that will affect the lives of women and children, and I think I'm going to go ahead and show up," she said.
Republican Sen. Shelley Moore Capito of West Virginia said she'll be celebrating International Women's Day. "But I'm planning on going to work -- and working hard," she added.
So why the color red?
"The red is symbolic of energy, the willingness to fight back," Frankel said of women's desire to speak out against what they consider damaging policies by Trump.
Alluding to the sea of pink that gathered on the National Mall for the Women's March, Rep. Jackie Speier, D- California, said at the rally Wednesday that the "pink tide is now turning red."
Clinton, progressive groups push female candidates
Former Democratic presidential candidate Hillary Clinton, increasingly re-entering the public eye, is set to speak Wednesday at an International Women's Day event in Washington.
On Tuesday at a Girls Inc. event
, said the full equality of women is "in big ways and small, the unfinished business of the 21st Century." She also urged women to run for office.
"Let us hope there is a wave of young women running for office in America," Clinton said. "And let's be sure we support them, in every way we can. Let's help them shatter stereotypes and lift each other up."
Emily's List, which backs female Democratic candidates, has launched a new program called "Run to Win" that triples the organization's staffing at the state and local level to recruit and train female candidates for office. The organization has heard from nearly 10,000 women interested in running for office since the 2016 election, said Jessica O'Connell, Emily's List's executive director.
"Just look at what we've seen since the Women's March -- women are speaking out at town halls, providing legal counsel to those affected by Trump's immigration bans, and standing up to Trump's agenda in the halls of Congress and in government offices across the country," O'Connell said.
Like the Women's March, "A Day Without Women" is led by major progressive groups.
NARAL Pro-Choice America -- which led 11 liberal groups in sending a letter Monday to Senate Democrats warning them that "we need you to do better" in opposing Neil Gorsuch's nomination for the Supreme Court -- is closing its office Wednesday so staffers can participate in the day of protest.
It is also sending members to participate in a protest outside the White House Wednesday over Trump's decision to reinstate the "global gag rule," which bars federal dollars from going to international health care organizations that perform abortions.
"We want to send a message to the world and to the country that a world without women doesn't function, and in order to allow women to be the wonderful members of society that we are that really powers the economy and our culture forward, we need policies in place to support us. And that obviously means policies to advance reproductive freedom," said Kaylie Hanson Long, NARAL's communications director.