In 2008, President Obama campaigned on a promise to raise the minimum wage. He hasn’t. Mitt Romney has said he supports pegging minimum wage to inflation, but recently backtracked, and he now opposes an increase.

According to the Economic Policy Institute, if Harkin has his way and the minimum wage was actually raised to $9.88 an hour, it would increase wages for 30 million Americans — 10 percent of the country.