Sanders was reacting to an op-ed from McConnell, published in the Courier-Journal, that called socialist ideas “dangerous.”

“They would raise your taxes and give the federal government vast control over your life. That’s why President Trump and I are fighting hard to stop them. As long as I’m Senate majority leader, these socialist schemes will never become law,” he wrote. McConnell name-dropped Sanders for stripping out a provision from the 2017 tax reform plan that would have exempted Kentucky’s Berea College. The small Appalachian liberal arts school, which does not charge tuition, received an exemption on the excise tax on endowment income as part of a budget deal in early 2018.

Sanders is a socialist. In a speech Wednesday afternoon in Washington, D.C., he outlined his vision for a new “21st century economic bill of rights,” a key element of the socialist platform he has long championed.

McConnell is up for reelection in 2020, which so far has attracted little serious competition. Republicans picked up a net gain of two seats in the Senate in the 2016 midterm elections, and have a 53-seat majority. Democrats have 45 seats, boosted by two independents, including Sanders, who caucus with them.

Sanders sits in second place, with 16.8%, in the latest RealClearPolitics average of polls for the Democratic presidential primary race, which has a wide 23-person field. Former Vice President Joe Biden is the front-runner.