Women earn just 77 cents to every $1 earned by men, proponents of new legislation say.

With a new poll may may have women once again moving toward Republican presidential candidate Mitt Romney, the Senate’s Democratic majority leader is reminding female voters that the GOP hasn’t ended its “war on women.”

Although President Obama had opened up a huge 19-point advantage among women just weeks ago in the midst of the debates over birth control and other women’s issues, a new Washington Post-ABC News poll finds that gap has shrunk to just 7 percent.

The “war on women” has been a potent rallying cry to attract more women voters to the Democratic side.

Senate Majority Leader Harry Reid of Nevada took to the Senate floor Wednesday to remind voters about the earlier Republican battles against women’s health care and access to contraception, and to challenge GOP senators to support the Paycheck Fairness Act.

Sen. Barbara Mikulski (D-Md.) reintroduced the legislation Tuesday.

“Although women make up nearly half of today’s workforce, they still earn only 77 cents on the dollar compared to their male colleagues,” Reid says. “And with an increasing number of women heading American households, this is a problem that affects children and families across the country.”

Reid calls the Senate Paycheck Fairness Act  “a logical extension of protections under the Equal Pay Act” which he says would help close the pay gap by helping women negotiate for equal pay and “creating strong incentives for employers to obey the laws already in place.”

Supporters of the Paycheck Fairness Act complain that despite current law, women are still blocked from knowing what their colleagues make. And when they fight for fair pay, they can lose their jobs.

In 19 of the 20 most common occupations for men or women, women earn less for the same work, those supporters say. In 264 of 265 major occupations, women’s median earnings are less than men, they add. And the pay gap costs women an average of $434,000 over their career, they say.

Mikulski, other Democratic senators, and independent advocates also held a separate press conference Wednesday to press for passage of the Paycheck Fairness Act. Mikulski made state-by-state data on the wage gap available online here.

Mikulski and others say her bill would build on the Lilly Ledbetter Fair Pay Act signed into law by Obama in 2009, which overturned the 180-day statute of limitations for women to contest pay discrimination. The Ledbetter law was the first legislation that Obama signed into law once in office as president. The Paycheck Fairness Act will close the loopholes that allow pay discrimination to continue in the first place, they say.

“Republicans deny they’re waging a war on women, yet they’ve launched a series of attacks on women’s access to health care and contraception this year,” Reid says. “Now they have an opportunity to back up their excuses with action.

“I hope they take that opportunity, and join Democrats as we send a clear message that America values the incredible contributions women make every day,” he adds.

Maine Republican Senator Olympia Snowe has announced her retirement.

A moderate Republican, who has often voted with Democrats in the Senate cited the extreme partisanship of recent years as her reasoning.

In a statement Snowe said, “Unfortunately, I do not realistically expect the partisanship of recent years in the Senate to change over the short term. So at this stage of my tenure in public service, I have concluded that I am not prepared to commit myself to an additional six years in the Senate, which is what a fourth term would entail.”

Notice of her retirement could be a “major setback for the GOP’s efforts to regain a majority in the Senate.” With Maine being a blue state, Snowe was considered as a moderate, to be the GOP’s only hope to hold the seat.

Among the names mentioned as possible replacements on the ballot for the GOP: 2002 gubernatorial candidates Peter Cianchette, 2010 gubernatorial candidate Steve Abbott, state Treasurer Bruce Poliquin, state Attorney General Bill Schneider, and Jock McKernan, Snowe’s husband and the state’s former governor. Businessman Scott D’Amboise was already challenging Snowe in a primary.

On the Democratic side, Reps. Chellie Pingree (D) and Mike Michaud (D) could run, as well as former congressman Tom Allen (D), who unsuccessfully challenged Sen. Susan Collins (R-Maine) in 2008.

The filing deadline is fast approaching: March 15.

Progressives are already crowing that Snowe is retiring and it can indeed be a win/win for Democrats, but let’s celebrate when we win her seat. Snowe has always been an ally on women’s issues, and with the surge in the war on women, we very much need a pro-choice, pro-women’s issues vote to replace her.

On the flip-side Democrats are losing their most moderate member, Senator Ben Nelson of Nebraska. Former Senator Bob Kerrey is said to be reconsidering running for Nelson’s seat.