Republicans asked the justices to step in after a federal court rejected their claims that the state's new congressional map violated the Constitution.
The Justice Department is sending prosecutors from Midwestern states to help the Minnesota U.S. attorney's office as it moves toward charges against state officials.
The U.S. Supreme Court on Monday handed President Donald Trump a defeat in his legal showdown with the most-populous U.S. state, declining to hear his administration's challenge to "sanctuary" laws in California that protect immigrants from deportation.
