Democratic attorneys general in at least five U.S. states have vowed to fight President-elect Donald Trump in the courts if he rolls back Obama-era regulations or adopts policies they view as infringing upon civil liberties. With Republicans controlling the White House and both chambers of Congress, the Democratic Party looks set to rely more heavily on top law officials in states they run to help keep a check on Trump’s exercise of power. Any efforts by a Trump administration to weaken consumer protection or climate change policies, for example, could lead to conflict between the states and the federal government, attorney general offices in Maryland, Virginia, Washington, Massachusetts, and New York told Reuters. In some instances, that could see them asking a federal judge to block federal action nationwide. “I view my role as being on the first line of defense against a Trump administration if it chooses to act in an unconstitutional fashion,” said Bob Ferguson, the Democratic attorney general of Washington state. When George W. Bush was president, Democratic states forced his administration to take the first step toward regulating carbon emissions for the first time. Michael Kelly, a spokesman for Virginia’s attorney general, Mark Herring, said that if a Trump administration “crosses the line and pursues actions that are illegal or violate the Constitution, Attorney General Herring will be ready to stand up and defend the rights of Virginians.” “The President-elect has made a number of promises that, if implemented, would violate the Constitution or Massachusetts law,” Massachusetts Attorney General Maura Healey said in a statement. “If the incoming administration chooses to try to act in ways that are unconstitutional, my office will take action to protect the rights and liberties of our residents and our state,” she said.