Sen. Sherrod Brown (D-Ohio) is moving closer to a presidential run, announcing Tuesday that he will embark on a "Dignity of Work Tour" this month to the crucial early voting states of Iowa, New Hampshire, Nevada and South Carolina.The big picture: Brown, a popular Democratic senator in a state that Trump won by 8 points in 2016, has long been considered a possible 2020 contender. In a statement announcing the tour, Brown said that "dignity of work is a value that unites us all. It's what I fight for everyday...and it's what we will fight for together on this tour around the country." Go deeper: Track who's running in 2020