Washington(CNN) For Bernie Sanders, slow and steady wins the fundraising race.
The Vermont senator began his bid for the Democratic presidential nomination last year with a sizable financial disadvantage compared to front-runner Hillary Clinton. By the end of last June, Sanders had raised just shy of $14 million for his campaign, less than a third of the $47.5 million Clinton had raised for hers.
But the Sanders campaign slowly and steadily eroded the former secretary of state's fundraising advantage. Sanders slightly edged Clinton in contributions in 2015's fourth quarter, but his fundraising operation didn't kick into high gear until 2016. His campaign has outraised Clinton's every month this year by at least 50%. In March alone, "Bernie 2016" received $44.7 million in contributions, compared to $26.3 million for "Hillary for America."
Now, Sanders and Clinton are essentially even in total campaign contributions, with each campaign bringing in more than $180 million for their bids by the end of March.
With the primary campaign entering its final weeks, both campaigns are spending at a frenetic pace. The Clinton campaign spent in March more than it raised in contributions, with a so-called burn rate of 107%. Sanders had a burn rate of 99% for March. For the campaign to date, the Sanders campaign has spent 91% of the money it raised, compared to 84% for the Clinton campaign.
Although Sanders has eliminated Clinton's financial advantage, the former first lady remains a fundraising powerhouse. In addition to her own campaign, Clinton also raises money for the "Hillary Victory Fund," a federal joint fundraising committee operated between the Clinton campaign, the Democratic National Committee, and a number of state parties. The fund has raised $60 million through the end of March and has transferred $12.7 million to the Clinton campaign. Any funds raised by a joint fundraising committee are divided among the sponsoring campaigns and parties using a predetermined allocation formula.
On Monday, the Sanders campaign wrote DNC chairwoman Debbie Wasserman-Schultz alleging that joint fundraising committee was improperly subsidizing the Clinton campaign.
DNC press secretary Mark Paustenbach said in response, "The DNC offered to engage in the same joint fundraising efforts with all the major presidential candidates early in the cycle and we welcome the efforts of the candidates to help raise money for the DNC and state parties now to ensure we can build out the infrastructure to win in November."
Sanders has his own joint fundraising committee with the DNC, the "Bernie Victory Fund," but as of March that account remained essentially inactive.
Clinton also has the support of outside groups known as "Super PACs," which can raise and spend unlimited amounts of money in support or opposition to a candidate but may not coordinate directly with a campaign. The primary Super PAC supporting Clinton is Priorities USA, which has raised more than $55 million in 2015 and 2016. The group also supported President Barack Obama in past cycles.
Sanders opposes Super PACs and he has largely based his campaign on the need for campaign finance reform.
Sanders likes to say that most of his fundraising has come from small donors where the average contribution is $27. He has criticized Clinton for larger donations, but the Clinton campaign said Wednesday their average donation size for March was $45.