Tuesday marks Equal Pay Day, a symbolic event dramatizing how much longer it takes a woman to earn as much as a man - and an annual opportunity for Democrats to lambast Republicans for inaction on the issue.

This time it comes amid a presidential campaign where the Republican front-runner, Donald Trump, has alienated female voters in droves, leading to GOP fears he could diminish the party's standing with that key constituency for years to come. Yet once again this year, as President Barack Obama and Democratic lawmakers trumpet their equal pay proposals at news conferences and briefings, Republicans have little to offer in return.