The head of the U.S. Chamber of Commerce vowed to wage war against Bay State U.S. Sen. Elizabeth Warren and “extremes in both parties,” comparing her to Steve Bannon and suggesting the pro-business lobbying group will pour money into the 2018 Senate race to defeat the progressive champion before she can mount a White House run.

“We’re going to fight back against the extremes in both parties — the Steve Bannons and the Elizabeth Warrens of the world — who do not represent the best interests of this country,” said Thomas Donohue, the president and CEO of the chamber in his annual “State of American Business” address. “We need to rebuild the middle in Congress.”

Hours later, Warren blasted Donohue as a “millionaire lobbyist,” and relished his criticism.

“Here’s the basic problem in Washington,” Warren tweeted. “Big business lobbyists are so used to running the place that they label anyone willing to stand up to them as extreme. When Tom Donohue and the @USChamber attack me for standing up to corporate interests, I know I’m doing my job.”

But Warren’s GOP foes used the speech as an opening to label her an uncompromising liberal purist.

“We used to have a fine tradition in our state of getting past the partisanship once an election is over,” said Republican Senate hopeful Beth Lindstrom. “Sadly, that is not the case with Elizabeth Warren.”

“I don’t think there’s a more radical, progressive, left-wing voice than Elizabeth Warren,” said state Rep. Geoff Diehl, another GOP U.S. Senate candidate, adding he believes the contest will attract national attention. “I’d expect this race will certainly get a lot of interest from groups, including the U.S. Chamber.”

The Chamber has picked plenty of fights with Warren before.

In 2012, the group spent approximately $300,000 targeting Warren in the 2012 Senate race against Republican Scott Brown, according to the Center for Responsive Politics.

When it endorsed Brown that summer, the chamber, in a statement from its political director, charged that “no other candidate in 2012 represents a greater threat to free enterprise than Professor Warren.”

The eventual Warren victory was symbolic of a brutal 2012 campaign cycle for the chamber, which spent $31.5 million on 35 candidates — with only seven races producing favorable outcomes.

Since then, the chamber and Warren have remained fierce political foes.

The Bay State senator was one of two authors of a Democratic Senate report in 2016 slamming the chamber for lobbying against the positions its members hold on tobacco use and climate change.

About a week later, Donohue ripped Warren in a speech, accusing her of trying to orchestrate a power grab.

“Senator Warren and her allies don’t have a reform agenda, they have a big government agenda,” Donohue said. “They want to centralize all decision-making in Washington, D.C.”