Sanders's haul in February far exceeded that of Democratic front-runner Hillary Clinton, who reported bringing in $30.1 million in February. That was the second month in a row that Sanders outraised Clinton.
As part of their pitch, Sanders's aides noted the fundraising numbers they report for March will be the last before key primaries in Wisconsin and New York.
In the race for the Democratic nomination, Clinton has built a formidable lead in the delegate count. Sanders, however, has vowed to stay in the race through the party convention, saying he is capable of mounting a comeback in a series of states more favorable to him.
Last weekend, he swept caucuses in Washington state, Alaska and Hawaii.