President Trump is restarting his effort to remove Federal Reserve Governor Lisa Cook from the central bank’s board, about a month after the Supreme Court blocked his first attempt. In a letter sent to Cook this week, the White House said the president was considering firing her over unproven allegations of mortgage fraud, reviving a fight that began last summer.

The White House gave Cook three weeks to respond to the allegations. Cook has not been charged with any crime and has repeatedly denied wrongdoing since the accusations first surfaced. Her attorneys have called the effort a pretext to gain political control over the independent central bank.

The renewed push follows a Supreme Court ruling in June that dealt Trump a setback on the same question. In a 5 to 4 decision, the justices upheld limits on the president’s power to remove Federal Reserve governors, citing the central bank’s unique structural independence from the executive branch. That same ruling, however, gave Trump broader authority to remove officials at other independent agencies, a split outcome both sides have since claimed as partial vindication.

An appeals court had already rejected an earlier version of Trump’s removal attempt ahead of a Fed policy meeting, leaving Cook in her seat as the central bank continued setting interest rate policy through the summer. Legal analysts say a second removal attempt built around the mortgage fraud allegations could force the courts to revisit the boundaries the Supreme Court just drew, this time on a fuller factual record.

Cook’s term on the Fed board is not set to expire for years, and her removal would be one of the most significant tests yet of presidential authority over the nation’s monetary policy institutions. The Federal Reserve has not issued a statement on the White House letter. Cook’s allies say they expect to seek emergency relief in court again if the White House moves to fire her once the three week response window closes.