TV ads sponsored by Democratic presidential candidate Bernie Sanders made up more than one-third of all presidential ads in the two weeks leading up to Tuesday's Wisconsin primary, a new report found.

Researchers with the Center for Public Integrity found the Democratic socialist paid for 5,700 of the 16,000 total ads that ran in that time span. Sanders' most popular ad "People Before Polluters" has run every 20 minutes since March 22.

Democratic front-runner Hillary Clinton, who trails Sanders by two points in a RealClearPolitics average of Wisconsin polls, purchased 3,300 ads.

There's no shortage of cash for Clinton, but Sanders pulled in $44 million last month compared to Clinton's $29 million, not including funds raised by her super PAC.

Clinton leads the delegate count and needs 263 more pledged delegates to secure the nomination before the July convention. Wisconsin will award 86 delegates, but not on a winner-take-all basis.