Former Maryland Gov. Martin O'Malley will make an official announcement about whether he will enter the 2016 Democratic presidential race May 30 in Baltimore, Fox News has learned. 

O'Malley, who served two terms as Maryland governor between 2007 and 2015, will make the announcement in the city he ran for eight years as mayor. If he runs, he would be the third Democrat to declare his candidacy for the White House, after former Secretary of State Hillary Clinton and Vermont Sen. Bernie Sanders. 

O'Malley has been a regular presence in early voting states since 2014. On Wednesday, he was in New Hampshire, where he indicated to reporters that he would make a formal decision on whether to run by the end of this month. Aides also confirmed to Fox that O'Malley will tell donors and supporters about his Baltimore announcement in a conference call Thursday night.

In another indication that he is on the verge of becoming an official candidate, O'Malley's political action committee has boosted its staffing and made several new hires in the last few weeks.

Later this week, O'Malley will attend meetings with longtime supporters in the Washington D.C. suburbs, some of Maryland's most solidly Democratic areas. 

In a closed-door meeting with top liberal activists and academics in New York on Monday, O’Malley pitched himself as the best shot progressives have at taking on Clinton in the primaries, a source tells Fox News. O’Malley cited his opposition to the Asia-Pacific free-trade deal, as well as other issues of importance to the progressive wing of the Democratic party as rallying points for his potential candidacy.

In New Hampshire Wednesday, O'Malley said Wednesday that many Americans living in cities are worse off than they were eight years ago and Democrats in Washington had wasted a chance to address poverty in the nation's urban areas.

Referring to the recent riots in Baltimore, O'Malley said "We've created whole swaths of Americans, particularly in American cities, who are worse off now than they were eight years ago. When people are unheard, when their country's economy treats them like they're unnecessary, like they're unwanted, like they're unneeded, this sort of anger erupts."

Fox News' Hillary Vaughn and the Associated Press contributed to this report.