Congress changed the law after the Supreme Court ruling and it was the first bill Obama signed into law.

“That was the first step but it can't be the last,” Ledbetter said. “Because women still earn just 77 cents for every dollar men make. Those pennies add up to real money. It's real money for the little things like being able to take your kids to the movies and for the big things like sending them to college. It's paying your rent this month and paying the mortgage in the future. It's having savings for the bill you didn't expect and savings for the dignified retirement you've earned.

“Maybe 23 cents doesn't sound like a lot to someone with a Swiss bank account, Cayman Island Investments and an IRA worth tens of millions of dollars," she continued. "But Gov. Romney, when we lose 23 cents every hour, every day, every paycheck, every job, over our entire lives, what we lose can't just be measured in dollars.”

When Obama was a senator he also voted for the Lilly Ledbetter Fair Pay Act in 2008.

“Three years ago, the House passed the paycheck Fairness Act to level the playing field for America's women,” Ledbetter said during her prime-time speech at the Democratic National Convention Tuesday. “Senate Republicans blocked it. Mitt Romney won't even say if he supports it. President Obama does.”