The price of insulin is going up, and Sen. Bernie Sanders (I-VT) refuses to take it lying down.

On Wednesday, the Vermont senator weighed in on a new class-action lawsuit taking aim at drug manufacturers.

"In the last 25 years, the pharmaceutical industry, major companies, have been fined some $35 billion for collusion, for fraud and for other illegal behavior," Sanders explained in an interview with "CBS This Morning."

"Coincidentally, [as insulin prices skyrocket]… the three major suppliers of insulin seem to be raising their prices at the same exact time at the same level. So I think you have to be very naive not to believe that there is collusion," Sanders added.

Sanders strongly advocated for a single-payer healthcare system during his presidential campaign and has since introduced legislation to allow Americans to buy less expensive medicine. But while Sanders' bill for allowing drug re-importation received bipartisan support, it was ultimately killed by 13 Democratic senators who voted against it.

Six million Americans depend on insulin to survive, and those without a way to pay are often forced to cross a border.

"Right now, in my state of Vermont, people go across the border, buy the exact same medicine they can buy in Vermont; they're getting it there for 50%, 60% lower prices," Sanders pointed out. "If those product can come in to pharmacists and distributors in this country, we can lower the price of prescription drugs very, very significantly."

Sanders' fight against Big Pharma is inextricably bound to his push for campaign finance reform.

"Five major drug companies last year made $50 billion in profits," Sanders said. "They have well over 1,000 lobbyists in Washington D.C. Their business model is greed, there are millions of people who cannot afford the prescription drugs their doctors prescribe… What the pharmaceutical industry is doing is an outrage….Their policies are literally killing people who cannot afford their medicine."

President Trump has also spoken out against the greed of the pharmaceutical industry, but has since backtracked after meeting with pharmaceutical lobbyists.

"Instead of negotiating drug prices down, [Trump] talked about cutting taxes for drug companies that already make billions on the backs of American consumers," Sanders noted in a Washington Post op-ed published February 2.

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