Washington — Democratic presidential candidate Senator Bernie Sanders denounced fellow candidate Pete Buttigieg over the big-money backers of his campaign, saying the money flowing into his campaign from billionaires is "precisely the problem with American politics."

Sanders, who emerged from the Iowa caucuses atop the Democratic field along with Buttigieg, said one area in which he plans to differentiate his campaign from Buttigieg's is by highlighting their donors. CBS News estimates both Sanders and Buttigieg have amassed the same number of national delegates following the caucuses, with 10 apiece.

"Last count, he has about 40 billionaires who are contributing to his campaign, the CEOs of the large pharmaceutical industries, the insurance companies and so forth," Sanders told "Face the Nation" on Sunday. "It matters enormously. That is precisely the problem with American politics."

Forbes estimates 40 billionaires and their spouses have contributed to Buttigieg's campaign.

Sanders argued Buttigieg's roster of donors means he wouldn't go after major corporations, such as pharmaceutical companies that make it difficult for Americans to afford crucial prescription drugs.

"When you have the heads of large pharmaceutical companies contributing to your campaign, you are not going to aggressively deal with the fact that in some cases we pay 10 times more for the same exact drugs as our friends in Canada and Europe pay," Sanders said. "You're not going to take on the collusion and the corruption of the drug companies who are ripping us off every single day."

During Friday's eighth Democratic debate in Manchester, New Hampshire, Buttigieg rebuffed the suggestion he would go easy on corporations and said he has grown his campaign without the support of corporate PACs.

"I have been very clear on both my record, where I have sued pharmaceutical companies, and what I'm campaigning for, and that includes raising wages and raising taxes on corporations and the wealthy," he said. "And as the only person on this stage who is not a millionaire or a billionaire, I know a thing or two about building a movement."

While Buttigieg had a slight advantage over Sanders in state delegate equivalents after the Iowa caucuses, Sanders noted Sunday he was the winner when it comes to the popular vote.

"Our campaign in an election which had about 180,000 people, we won the popular vote by 6,000, first ballot. On the realignment process we won by 2,500," Sanders said. "So in all due respect to the media and otherwise I kind of think that when you win the popular vote by 6,000 votes you win the election."

Sanders and Buttigieg, along with many of the other candidates in the Democratic field, are currently campaigning in New Hampshire, which is holding its first-in-the-nation primary Tuesday.