(CNN) California Gov. Gavin Newsom slammed the Trump administration and Republicans for their "complete silence on state's rights, but also free enterprise" in light of President Donald Trump's decision to curtail state-set emissions standards.

"They're calling private sector corporations to the mat and threatening them," Newsom, a Democrat, told CNN's Don Lemon on Wednesday night on "CNN Tonight."

"I don't think this, I know this from the personal conversations I've had and by the actions of the Department of Justice," he continued. "What happened to the Republican Party?"

Newsom, who frequently spars with the President, made the comments as Trump scraps with California's Democratic officials over auto-emission standards and the state's homeless crisis. Earlier this month, the Trump administration opened an antitrust investigation into four auto companies -- Ford, Honda, BMW and Volkswagen -- that agreed with the state of California to raise their fuel economy standards in coming years.

"Federalism be damned; state rights, 10th Amendment be damned; Ronald Reagan, Richard Nixon be damned," Newsom said Wednesday when asked why he thought a Republican administration was exerting its power over a state-level decision -- traditionally a cornerstone of conservative policy.

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