DONALD TRUMP is plunging the US into another constitutional row by sacking a Federal Reserve governor, who says he has no authority to do so.

Mr Trump’s announcement would be the first presidential firing of a Federal Reserve governor in history. He said on social media on Monday night that her sacking, attributed to accusations of mortgage fraud levelled against her by one of his allies, was effective immediately, but Governor Lisa Cook retorted: “President Trump purported to fire me ‘for cause’ when no cause exists under the law, and he has no authority to do so. I will not resign.”

The US central bank is, like the Bank of England since the late 1990s, “politically independent,” a mechanism to ensure monetary policy is beyond democratic control.

Its decisions do not require approval from the president or Congress, but board members are appointed by the president and can be dismissed by them “for cause,” interpreted as meaning for some kind of wrongdoing. Ordinarily this would involve a process in which Ms Cook could respond to allegations.

Critics believe the sacking is motivated by Mr Trump’s desire to lower interest rates. Ms Cook’s refusal to resign, and hiring of lawyer Abbe Lowell, make it likely the case could go to the Supreme Court.

Democrat Senator Elizabeth Warren called the act “the latest example of a desperate president searching for a scapegoat to cover his own failure to lower costs for Americans. It’s an authoritarian power grab.”

Mr Trump has pushed to extend presidential power in multiple fields, testing its constitutional limits.

Lawsuits have begun over his assumption of federal control over the California National Guard and deploying it, and US marines, to that state’s biggest city Los Angeles in June to suppress protests against his mass deportations of immigrants. The National Guard have since been deployed to Washington DC, and he has threatened to do so in Chicago and New York too.

Though soldiers are not supposed to be used for domestic policing in the US, his eldest son Donald Trump Jnr says the National Guard could be deployed to “Portland, Seattle, the other craphole cities of the country” where Democratic administrations have allegedly allowed murder rates to soar “through the roof.”