Former Maryland Governor Martin O'Malley on Saturday entered the race for the Democratic presidential nomination, joining Vermont Senator Bernie Sanders in challenging former Secretary of State Hillary Rodham Clinton.

A crowd of about 1,000 people gathered in Federal Hill Park in Baltimore, where he served as mayor before he was elected governor, to hear O'Malley's announcement.

“I'm running for you,” O'Malley told the crowd, his wife Katie Curran O'Malley and their four children by his side.

O'Malley positioned himself as a progressive ready to take on Wall Street.

“I've got news for the bullies of Wall Street. The presidency is not a crown to be passed back and forth by you between two royal families,” he said, a reference to Goldman Sachs CEO Lloyd Blankfein's recent comments that he would be “fine” with either Clinton or former Florida Governor Jeb Bush as the next president.

After his announcement, O'Malley headed to Iowa, where he spoke at a union hall in Davenport.

“Tell me how it is that not a single Wall Street CEO was convicted of a crime related to the 2008 economic meltdown? Not a single one,” he said. “Tell me how it is that you can get pulled over for a broken tail light, but if you wreck the nation's economy you are untouchable?”

Like Clinton and Sanders, O'Malley supports marriage equality. As governor, he signed a gay marriage bill, which was later upheld by voters in a referendum. Last year, he signed a law outlawing discrimination against transgender people in the areas of employment, housing, credit and public housing.