WASHINGTON (Reuters) - U.S. Senator Kamala Harris, one of two dozen Democrats vying for the 2020 presidential nomination, on Monday proposed closing the gender pay gap by requiring companies to disclose pay data and secure an “equal pay certification” or be fined.

Harris’ proposal aims to shift the burden from workers, who now must prove pay discrimination by employers, to corporations, which would have to show they eliminated pay disparities between men and women doing work of equal value.

In 2017, full-time, year-round working women earned 80% of what male counterparts earned, the U.S. Census Bureau says, and minority women earned even less.

At a college rally in Los Angeles on Sunday, Harris decried the pay gap between men and women. “This has got to end,” she said, to audience cheers.

Harris said her plan would incentivize corporations to close the pay gap, because “There will be penalties if they don’t.”

Under Harris’ proposal, which would require approval by the U.S. Congress, companies with 100 or more employees would give their pay data to the Equal Employment Opportunity Commission.

They would also have to prove existing pay gaps were not based on gender but merit, performance or seniority, and commit to policies barring mandatory arbitration pacts for job disputes and questions about salary history during hiring.

Companies falling short of the criteria would be fined 1% of their profits for every 1% wage gap found after adjusting for variables such as experience and performance.

Harris’ campaign said it estimated the plan would generate $180 billion over a decade, with revenue falling as new pay policies are adopted. The fines would go to offset the cost of universal paid family and medical leave policies she backs.

In an acknowledgement that implementing such legislation would be difficult, if not impossible, if Democrats did not also maintain control of the House of Representatives and win control of the Senate, Harris outlined how she would use the president’s executive authority to force companies competing for federal contracts worth $500,000 or more to obtain the certification.

Harris’ campaign said 28 million U.S. workers would be covered by such executive action.