Fredreka Schouten

USA TODAY

Bernie Sanders had the best fundraising month of his campaign in February, and it was also his costliest.

The Vermont senator took in $43.5 million, topping the haul of his rival Hillary Clinton. But he also outspent Clinton last month, racing through $40.9 million and whittling away at the money he has available to battle her through March for the Democratic presidential nomination.

Sanders started March with $17.2 million in cash reserves, while Clinton had nearly $31 million, according to reports filed Sunday with the Federal Election Commission.

Clinton swept all five states that staged nominating contests last week, extending her delegate lead over Sanders. Democrats in Idaho, Arizona and Utah vote Tuesday.

Hillary Clinton wages costly fight with Bernie Sanders