In just 100 days after the bill passed the House, women working full time were paid $159 billion dollars less than men were, according to the Center for American Progress. Those are dollars that could help women and families pay for housing, child care, and health care and contribute to our country’s economic growth.

Overall, women take home just 80 cents for every dollar earned by men, according to a National Partnership for Women and Families analysis of census data. The news for women of color is even worse. For example, Hispanic women earn only 62% of what white men make and 86% of what Hispanic men make, according to the Institute for Women’s Policy Research (IWPR). And black women only make slightly more: 65% of white men’s earnings and 89% of black men’s earnings.

And the disparity occurs across all occupations. While people may assume that lower-wage employees face the highest burden, according to IWPR, “The occupation with the largest gender wage gap is ‘securities, commodities, and financial services sales agents’ in 2018; women’s median weekly earnings for full-time work in this occupation were just 63.9% of those of men’s.”

The wage gap is a blatantly unfair vestige of a patriarchal labor system that haunts women’s economic potential throughout their lives. It leads to decreased earnings once women reach retirement and contributes to higher rates of debt. A recent analysis of more than 500,000 users by the banking and investing app Stash even found that women pay a disproportionate amount of banking fees, with the Stash CEO pointing to the wage gap as a probable cause.

That is why we desperately need the Paycheck Fairness Act, which has been introduced in the House for two decades by Rep. Rosa DeLauro. The act would help address pay disparities in four very important ways. First, it will prohibit hirers from using salary history in determining salary offers. Currently, if a woman has been underpaid in a previous job, she is at risk of continuing to be underpaid through the rest of her career.

Second, the bill protects employees from retaliation for discussing salaries with their colleagues and precludes employers from firing employees for sharing information. This practice is often the only way most women can discover pay disparities, as wages are typically kept private by employers.

Third, the act will require employers to prove any pay disparities existing between men and women are a business necessity and job-related, therefore ensuring equal pay for equal work.

Fourth, the law will update class action lawsuit provisions under the Equal Pay Act so that class members in a wage discrimination case will automatically be considered part of the class unless they choose to opt out. According to the American Bar Association, “This change will make it easier to combat systemic sex-based wage discrimination and provide relief to all those who [sic] injured by it.”

These basic provisions would provide crucial standards for employers to follow and help to create safe spaces for women to discover and address paycheck inequities with less fear of retaliation. 

Poll after poll shows overwhelming support for equal pay. Yet still the Senate will not move forward.

Eleven states are trying to pick up the slack, with laws seeking to address the wage gap and discrimination, reports Bloomberg Law. Many of these laws, occurring everywhere from red-state Alabama to blue-state New York, have bans on salary history questions in job applications and shield employees from retribution for sharing salaries. But while laudable, these efforts are no substitute for a strong national standard that would provide requirements for all businesses, including those operating in multiple states.

Systemic wage discrimination must end in our culture. NOW urges the public to stand in solidarity with the Paycheck Fairness Act by calling on their senators to co-sponsor the bill and demand a full Senate vote. We must stop blocking the full participation of female employees in the workplace and in the economy. It is time for the Senate to bring this bill’s 20-year journey for wage parity to a victorious conclusion for working women across the country.

Toni Van Pelt is the president of the National Organization for Women.

More opinion in Fortune:

—Girls Who Code CEO: Men need to be brave in the service of women
—Delivering on the promise of purpose beyond profits
—Regulate fintechs for what they do, not what they don’t
—Retaining good employees is tougher than ever, but offering paid family leave can help
—Supporting LGBT employees is a patriotic act
Listen to our audio briefing, Fortune 500 Daily