Former Maryland Gov. Martin O'Malley announced Saturday that he will seek the 2016 Democratic nomination for the presidency, bringing the field to three candidates.

"Today, to you, and to all who can hear my voice, I declare that I am a candidate for the president of the United States and I'm running for you," O'Malley told a crowd of about 1,000 people at Federal Hill Park in Baltimore, where he served as mayor for two terms before his tenure as governor, reported The Associated Press.

O'Malley, 52, faces two formidable challengers for the nomination, with many Democratic officials and donors focusing on former Secretary of State and Democratic frontrunner Hillary Clinton, and more liberal voters favoring Vermont Senator Bernie Sanders.

During his announcement, O'Malley called for boosting the federal minimum wage, comprehensive immigration reform, fighting climate change, and vowed to legalize gay marriage in all 50 states. He offered a "new foreign policy of engagement and collaboration," but economic equality was at the heart of his speech, as he stressed his desire to close the gap between rich and poor in America.

"The American Dream seems for so many of us to be hanging by a thread," O'Malley said as he pledged to close "a growing gap of injustice in our country" if he becomes president.

"Powerful, wealthy special interests here at home have used our government to create - in our own country - an economy that is leaving a majority of our people behind. Our economic and political system is upside down and backwards and it is time to turn it around."

He continued: "We cannot rebuild the American dream here at home by catering to the voices of the privileged and the powerful. Let's be honest. They were the ones who turned our economy upside-down in the first place. And they are the only ones who are benefiting from it."

O'Malley, who served as governor from 2007 to 2015, presented himself to the left of Clinton - younger and more willing to take a stand against Wall Street, which he took a swipe at Clinton for during his speech.

"Goldman Sachs is one of the biggest repeat-offending investment banks in America," he said. "Recently, the CEO of Goldman Sachs let his employees know that he'd be just fine with either Bush or Clinton. I bet he would. Well, 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."

"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," O'Malley said.

A Quinnipiac University Poll released this week found that 1 percent of Democrats support O'Malley. Clinton led the field with 57 percent, followed by Sanders at 15 percent and Vice President Joe Biden at 9 percent.

Eighty percent of Democratic voters in the poll said they didn't know enough about the former governor to form a strong enough opinion.