Colorado election law lets candidates of large parties choose whether to get on the primary ballot by winning substantial support at a party meeting, or petitioning.  Candidates must decide in January of an election year which method to use.

Michelle Ferrigno Warren, a Democrat, running for U.S. Senate, decided to use the petition method, which requires 10,500 signatures.  The petitioning period runs from late January through March 17.  Due to the health crisis, she was not able to collect enough signatures.  She filed a lawsuit in state court, Warren v Griswold, which is pending in Denver District Court.