Sen. Bernie SandersBernie SandersWATCH LIVE: Trump holds Calif. rally after backing out of Sanders debate Sanders blasts Trump: 'What are you afraid of?' Tech firm offers M for Trump-Sanders debate MORE (I-Vt.) will officially launch a bid for the White House on Thursday.
A Democratic source close to the senator confirmed to The Hill that Sanders will announce his candidacy for the Democratic presidential nomination in a statement later this week, before heading back to his home state for a campaign kick-off event early next month.
The former secretary of State has a huge lead over the field of potential Democratic contenders, taking 62 percent support in the latest Fox News poll released last week.
Sen. Elizabeth WarrenElizabeth WarrenVerizon, striking unions reach agreement in principle What Bernie needs to do right now An all-female ticket? Not in 2016 MORE (D-Mass.), who insists that she’s not running for president, came in second at 12 percent, followed by Vice President Biden at 9 percent and Sanders at 4 percent.
Still, many Democrats will be happy to see Clinton get at least a token challenger. They believe it could keep Clinton sharp as she prepares for the general election, and Sanders is a liberal favorite who will challenge her on policy issues from the left.
Vermont Public Radio first reported his decision.
—This post was updated at 5:15 p.m.