Bernie Sanders just demonstrated that Super PACs and a handful of billionaire donors might not actually have complete control over American elections after all. The senator from Vermont, who has repeatedly called for campaign finance reform to get big money out of politics, became the first non-incumbent presidential candidate in US history to receive two million donations at this point in the election, his campaign announced Wednesday evening.

Sanders has managed to build his Democratic presidential campaign using a wide network of small-dollar, individual donations averaging less than $30 each. His outspoken rejection of wealthy donors, which he says allows him to avoid being beholden to special interests, has been a point of pride for his campaign and a large reason for the groundswell of grassroots support for him.

The Sanders campaign reached the two million benchmark after a fundraising push this week. More than $3 million was raised since Monday, according to the campaign, with $1.6 coming in since Wednesday alone.

"Over two million contributions have been made to the only campaign that rejects a corrupt campaign finance system," Sanders said in a video that his campaign released to announce the milestone. "You can't level the playing field with Wall Street banks and billionaires by taking their money."

Even President Barack Obama's remarkable 2008 run, which was historic for its grassroots fundraising effort, only managed to reach the one million mark in individual donations by the time of the Iowa caucuses.

By the end of 2011, Obama's re-election campaign had received 2.2 million donations, which the Sanders campaign said could be beaten by their candidate before the end of this year.

Sanders's striking ability to fund his campaign through millions of small-dollar donations is especially significant in an election that is on track to be the most expensive in history. He has long refused to accept Super PAC money, attend fancy fundraisers, or court mega-donors, as most of his peers do. Sanders and Donald Trump are the only two major candidates in the current presidential election who do not have an affiliated Super PAC — an organization made up of the candidate's close allies that collects contributions and essentially functions as an unofficial extension of the campaign itself — backing them, according to Politifact.

But thanks to campaign finance laws, candidates cannot stop anyone from creating a Super PAC to support them, which several loyal Bernie fans have taken it upon themselves to do.

Two pro-Sanders PACs, Progressive Voters of America and Collective Actions, have raised slightly more than $25,000, according to the most recent Federal Election Commission filings. This amount pales in comparison to the other candidates in the race — outside groups supporting Hillary Clinton and Jeb Bush, for instance, have raised more than $20 million and $100 million, respectively.

Sanders has a total of $41 million in his war chest, which is considerably less than the other candidates in the race. Bush has the most money of any candidate, with his campaign and supportive groups having raised more than $125 million, followed by Clinton with about $100 million, according to FEC filings.

Just 1.7 percent of Sanders's total funds came from donors giving the maximum contribution of $2,700, his campaign said, compared with nearly 62 percent of Clinton's total haul.