Sen. Bernie Sanders (I-Vt.) announced on Wednesday that he'll run for president of the United States in 2016.
"I am running for president," Sanders told The Associated Press. "People should not underestimate me... I've run outside of the two-party system, defeating Democrats and Republicans, taking on big-money candidates and, you know, I think the message that has resonated in Vermont is a message that can resonate all over this country."
Sanders will make a more formal announcement about his presidential campaign on Thursday.
Sanders is the first official challenger for the Democratic nomination to Secretary of State Hillary Clinton, who announced her candidacy earlier this month.