President Obama took two steps Tuesday aimed at narrowing the wage gap between men and women, ordering federal contractors to let their employees share salary information with one another and to disclose more details about what their employees earn.

"A woman has got to work about three more months in order to get what a man got because she’s paid less. That's not fair. That’s like adding an extra six miles to a marathon," the president said, speaking at an event with Lily Ledbetter, who became a champion of pay equity after suing Goodyear Tire & Rubber Co. for gender discrimination. "It's not right and it ain’t right."

The executive order and presidential memorandum, part of a broader effort by the White House to highlight the challenges women face in the workforce, came as Senate Democrats pushed for a floor vote on the Paycheck Fairness Act, which includes reforms like the ones that Obama is  now applying to federal contractors.

"Pay secrecy fosters discrimination and we should not tolerate it--not in federal contracting or anywhere else," Obama said, noting the Senate was poised to consider legislation Wednesday that would broaden the protections he was issuing under his executive authority. "They’ve got a chance to do the right thing.  And it would put sensible rules into place, like making sure employees who discuss their salaries don’t face retaliation by their employers... This should not be a hard proposition."

Senate Democrats are hoping paycheck policy will be a smart play by focusing attention on the fight for equal pay. However, opponents say it's less about the wage gap and more about politics. (Pamela Kirkland/The Washington Post)

Even as Democrats seized on “National Equal Pay Day” as an opportunity to showcase their gender policy agenda, however, Republicans and some academics debated how best to calculate the pay difference between men and women in the United States. The vast majority of Americans agree that the  country lacks a level playing field at work, according to a Pew Research Center survey last fall, which found 72 percent of women and 61 percent of men said “this country needs to continue making changes to give men and women equality in the workplace."

While Obama described the gender pay gap as women earning 77 cents for every dollar men earn, this statistic does not fully capture the factors that contribute to the discrepancies between men's and women's salaries in the United States. A Bureau of Labor Statistics report shows that younger women have only a 4 percent pay gap with their male counterparts, largely because they have not taken time off work to care for children.

Thirty-nine percent of mothers say they have taken a significant amount of time off from work, and 42 percent have reduced their work hours to care for a family member, according to Pew Research, while 27 percent of mothers may have quit work altogether for that reason. By contrast, 24 percent of fathers say they have taken a significant amount of time off to care for a child or other family member. All of this contributes to lower earnings for women, along with the fact that women tend to be concentrated in lower-earning professions.

The Republican National Committee issued a memo Tuesday criticizing the Democrats' approach to the issue, saying their executive and legislative proposals don't address the fact that women and men are often concentrated in different professions.

"There’s a disparity not because female engineers are making less than male engineers at the same company with comparable experience," the memo says. "The disparity exists because a female social worker makes less than a male engineer — just as a female engineer would out-earn a male social worker. The difference isn’t because of their genders; it’s because of their jobs. The 'Paycheck Fairness Act' wouldn’t change that."

However, women are twice as likely to say they face gender discrimination in the office: Pew Research found that 18 percent of women, compared with 10 percent of men, say they had been discriminated against at work because of their sex.

And most Americans appear sympathetic to the argument the president is making on the question of pay secrecy. A recent poll by the Robert Morris University Polling Institute in Pittsburg found two-thirds of respondents believe their employers hid information about their coworkers’ salaries to hide gender comparisons that favor men.