New York CNN  — 

Vermont Sen. Bernie Sanders will make an announcement on Thursday about his intentions to run for president, a source close to his thinking tells CNN.

Sanders, an independent senator who caucuses with Democrats, has been inching towards a presidential run for months by traveling the country and speaking to liberal groups in critical presidential states like Iowa, New Hampshire and South Carolina.

READ: A Sanders announcement ‘within days’

Sanders’ Senate office would not comment on his 2016 plans, but the source close to the senator said Sanders’ Thursday announcement will likely be subdued.

The news of Sanders’ Thursday announcement was first reported on Vermont Public Radio.

Sanders is expected to run to the left of Hillary Clinton, the prohibitive Democratic favorite. The senator is a vocal proponent of getting unaccounted money out of politics and government-provided universal health care. He has also advocated breaking up the Wall Street banks and investing billions in infrastructure.

Earlier this month, Sanders told CNN that he was “reasonably close” to a decision on 2016.

“The clock is ticking,” he said at an event in New Hampshire. “If we do it, I’ve got to get out there. So I think we are looking at an announcement in the pretty near future.”

For much of the last six months, the senator has been teasing a run, while also acknowledging that his bid would be primarily uphill. When asked about 2016 in the past, Sanders has been quick to detail all the reasons a run would be difficult – money, organization, name identification – before discussing why he could do it.

Clinton leads the Democratic field in every poll. In March’s CNN/ORC poll, Clinton garnered 62% support, compared to Sanders’ 3%.

Bernie Sanders Senate hallway
Here comes Bernie Sanders
01:23 - Source: CNN