Recent polls have shown a significant gender gap with women more likely to support Obama than presumed Republican nominee, former Massachusetts Gov. Mitt Romney.
Obama said women still make on average only 77 cents for every $1 earned by men. Black women get 64 cents for every $1 earned by a white man and Hispanic women 56 cents.
"National Equal Pay Day represents the date in the current year through which women must work to match what men earned in the previous year, reminding us that we must keep striving for an America where everyone gets an equal day's pay for an equal day's work," he said.
Obama pointed up some of his earlier steps to reduce the wage gap, including signing the Lily Ledbetter Fair Pay Act and setting up a National Equal Pay Task Force.