Bernie Sanders is receiving big money support from a super PAC, whether he likes it or not.

Nurses United for Patient Protection, a super PAC tied to the National Nurses United union that backs Sanders, has spent over $569,000 supporting the socialist candidate, according to reports.

National Nurses United has been one of Sanders' most vocal supporters during the primary season, sending out multiple press releases and statements supporting the Democratic challenger's policies or bashing Hillary Clinton's stances on the issues.

The group's PAC has spent hundreds of thousands producing printing materials and creating print and online ads for the candidate, with large ad buys in Iowa, New Hampshire, South Carolina and Nevada.

Sanders repeatedly reminds voters that "[u]nlike virtually every other campaign, we don't have a super PAC," as most other serious contenders for the Democratic or Republican nomination do. Instead, his campaign boasts of its grassroots efforts and what he calls his "super pack" of supporters. His campiagn even has a page on the candidate's website entitled '"I Don't Have a Super PAC."

Nurses United for Patient Protection's primary donor is National Nurses United, but it also has another donor, Progressive Kick, which run's donor-matching programs for progressive issues. During the 2014, the PAC spent over $2.3 million and during the 2012 elections it spent $500,000. The super PAC and the affiliated union aims to advocate for Medicare spending and improve workers rights.

The super PAC backing Sanders has received is a small sum in comparison to the $40 million Hillary Clinton super PACs have collected on behalf of Hillary Clinton or $31 million for Jeb Bush.