Senate Republicans on Wednesday blocked a Democratic bill that would have required companies to prove that wage discrepancies are not based on gender.

The "Paycheck Fairness Act," is a key measure in the Democratic agenda, which lawmakers admit has little chance of passing but believe will contrast their party with the GOP ahead of the critical 2014 midterm elections.

The measure failed a test vote by a 53-44 margin, seven votes shy of the required 60 vote threshold needed to start debating the bill.

Every Senate Republican present voted against the measure, including the three female GOP lawmakers, who said the Democratic bill would have curbed flexibility and led to lower wages among workers. Independent Angus King, who caucuses with the Democrats, also voted no.

Current law already bans gender-based pay discrimination. The Senate bill would have further equipped the Labor Department to find cases of wage disparity suffered by women and minorities, and it would have made it easier to file lawsuits and receive huge payouts from companies found guilty of such discrimination.

Republicans on Tuesday offered a series of amendments to the legislation, including a measure that would have allowed companies to offer time off in place of overtime pay, which is allowed in the federal workforce.

Republicans said while women are seeking pay equity, they also want the option of taking more time off from work.

“What we are saying is let's give working women in the private sector the same kind of flexibility they have here in government,” Senate Minority Leader Mitch McConnell, R-Ky., said.

Other GOP provisions would have banned retaliation against workers who discuss pay, reformed job training by eliminating duplicative programs, and required employers to inform employees of their right to earn equal pay regardless of gender.

Senate Majority Leader Harry Reid dismissed all of the amendments. He said the overtime provision would lead to employers abusing the system to deny workers overtime pay.

“Republicans always want to change the subject,” Reid said. “Why don’t we have a debate on this: Do women deserve to have equal pay as men?”

The White House and Senate Democrats have touted a figure claiming that women earn only 77 cents for every dollar a man makes. The figure has been largely discredited because it does not take into account job description and hours worked.

Studies show there exists at least some pay disparity between men and women and Democrats believe the legislation is a political winner for them because they say it shows their party cares most about women in the face of obstructionist Republicans.

Reid voted “no” on the measure, a parliamentary move that will allow him to take up the bill again, which Democrats plan to do as the 2014 election battle intensifies.

Democrats are struggling to hold onto their Senate majority, with a half-dozen incumbents at risk of losing in red states where Obamacare has been unpopular.

The party is now hoping to change the subject.

“What I want everyone to know, though we lost the vote, we refuse to lose the battle,” Sen. Barbara Mikulski, D-Md, said. “Women of America, we say to you, join in this fight, make your voices heard.”