Democratic presidential candidate Bernie Sanders speaks during a recent rally in Norfolk. (Jonathan Newton / The Washington Post)

FORT COLLINS, Colo. -- The campaign of Democratic presidential hopeful Bernie Sanders said Monday that it had already raised $36 million this month and was aiming to top the $40 million mark by the end of February’s final day.

If successful, the Vermont senator would nearly double his take from January, a sum that was viewed as astonishing at the time for a candidate who relies almost entirely on online contributions to fuel his race against Hillary Clinton.

The fundraising push comes as Sanders head into a crucial test of electoral strength on Tuesday, when he and Clinton will compete in primaries and caucuses in 11 states, just days after the former secretary of state trounced Sanders in South Carolina.

Sanders held a rally Sunday night in Colorado and has events planned Monday in Minnesota and Massachusetts.

To spur supporters to give more money, Sanders’s campaign has set up a Web page tracking his progress toward $40 million for February.

Between the launch of his campaign 10 months ago and the end of January, Sanders reported raising $94.8 million.