Democrats in the U.S. Senate will renew their push for equal-pay legislation next week with the Paycheck Fairness Act, a bill with an embattled history that would help close the wage gap between men and women that experts say costs the average woman about $434,000 over the course of her career.

Like other recently proposed legislation focusing on women's issues, the measure will probably spark a fight in a bitterly partisan Congress, particularly in an election year when Democrats and Republicans alike are doing their best to frame themselves as the pro-women party.

How the GOP will bolster its standing among the nation's female voters by opposing equal-pay legislation is unclear, but Senate Majority Leader Harry Reid, D-Nev., is already preparing for the possibility, scheduling a cloture vote for next week to prevent a Republican-led filibuster.

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. Now they have an opportunity to back up their excuses with action, Reid said on the Senate floor after the bill was reintroduced on May 23, according to multiple reports.

In anticipation of the vote next week, here are four things to know about the Paycheck Fairness Act:

Pay Inequity Still Plagues American Women

While the federal government has had laws intending to combat wage disparity based on sex since the passage of the Equal Pay Act in 1963, the pay gap has closed at the rate of less than half-a-penny per year. In the year of the landmark law's passage, a woman earned 59 cents for every dollar earned by a man on average: The equivalent figure increased only to about 77 cents on the dollar in 2010, according to the U.S. Census Bureau and Bureau of Labor Statistics.

As a result of pay inequities, the Center for American Progress estimated the average female worker loses about $434,000 in salary or wages compared with men over a 40-year period, a particularly grueling cost since more than 12 million families with children in the U.S. rely primarily on women's earnings.

Pay discrepancies are even more glaring among minority women. On average, African-American women earned 72 cents for every dollar earned by men in 2010, according to the AFL-CIO Department for Professional Employers, while Hispanic women earned even less, 62 cents on the dollar.

Only Asian-American women came close to income on par with men employed in a similar position, with the women bringing in 94 cents for every dollar earned by men. However, they earn only 81.8 percent as much as Asian-American men.

A 2011 analysis from the Chairman's Staff of the Joint Economic Committee concluded there is a gender pay gap in every state among full-time workers. There is not one state where women, on average, earn more than men in comparable positions.

It Closes Loopholes In Existing Wage-Discrimination Laws

The Paycheck Fairness Act would build on the Lily Ledbetter Fair Pay Act of 2009, which ensures women's 180-day statute of limitations for filing an equal-pay lawsuit resets with each discriminatory paycheck, to close loopholes in the Equal Pay Act.

The bill would require employers to prove pay disparity for comparable work is truly related to job performance, as opposed to an employee's sex.  It also prohibits employers from taking legal action against employees for sharing salary information with co-workers -- something that is permissible under current law -- and allows women to seek punitive damages for pay discrimination, on top of back pay.

Finally, the legislation aims to empower women through a grant program intended to help working women improve salary-negotiation skills. Studies overwhelmingly show that women are typically not as successful as men when it comes to compensation negotiations.

Women's Wages Stop Growing A Decade Before Men

An analysis from PayScale, a company that collects data on salaries, reported that typical female college graduates hit their pay ceiling at age 39, according to the Washington Post. By that age, they earn an average of $60,000 -- the same amount earned by female, college-educated, full-time workers at age 50, 60, and onward.

In comparison, college-educated men continue getting raises until about age 48, when their average salary plateaus at a considerably higher $95,000. Although it is unclear why employers stop giving employees raises after they hit a certain age, it is quite apparent that women hit that glass ceiling far sooner than men do.

Paycheck Fairness Act Is Not New

The legislation was initially introduced by former Sen. Hillary Clinton, D-N.Y., who is the current U.S. secretary of state, in 2005, specifically to address the limitations of the original Equal Pay Act. The U.S. House of Representatives narrowly passed the bill -- with little bipartisan support from Republicans -- in January 2009, but the Senate failed to move the measure forward after the chamber came two votes short of its passage. No Senate Republican voted in favor of the bill.