Sen. Bernie Sanders (I-VT) publicly thanked the Koch brothers in a Monday tweet for “making the case for Medicare for all,” referring to a study analyzing the cost of single-payer health care.

Thank you, Koch brothers, for accidentally making the case for Medicare for All! pic.twitter.com/speuEL6ETC — Bernie Sanders (@SenSanders) July 30, 2018

Sanders thanked the Koch brothers for accidentally arguing that his plan would cut healthcare costs by $2 trillion over 10 years, referring to a study conducted by researchers at the libertarian Mercatus Center at George Mason University—which is backed by the billionaires Charles and David Koch.

“Let me thank the Koch brothers, of all people, for sponsoring a study that shows that Medicare for All would save the American people $2 trillion over a 10-year period,” Sanders tweeted.

The study argues that Sanders’ plan for universal health care would raise federal government spending by $32.6 trillion between 2022 and 2031, but also noted that overall federal healthcare spending would decline by more than $2 million.

President Trump dismissed the billionaire Koch brothers as “a total joke” in a Tuesday morning tweet, criticizing them for being against “strong borders and powerful trade.”

The globalist Koch Brothers, who have become a total joke in real Republican circles, are against Strong Borders and Powerful Trade. I never sought their support because I don’t need their money or bad ideas. They love my Tax & Regulation Cuts, Judicial picks & more. I made….. — Donald J. Trump (@realDonaldTrump) July 31, 2018

….them richer. Their network is highly overrated, I have beaten them at every turn. They want to protect their companies outside the U.S. from being taxed, I’m for America First & the American Worker – a puppet for no one. Two nice guys with bad ideas. Make America Great Again! — Donald J. Trump (@realDonaldTrump) July 31, 2018

The Kochs and their officials have openly criticized many elements of Trump’s “America First” agenda. Charles Koch and his brother David told donors at a recent conference that Trump’s tariff’s on steel and other imported goods “unfair” to foreign workers.