Warren flew home to Boston late Tuesday, after a Detroit rally. She has no public events scheduled for the day. A senior campaign official told The Hill she would meet with staff to gauge her remaining chances.

"Elizabeth is talking to her team to assess the path forward," the campaign aide said.

By the end of the night, Warren had accumulated an estimated 50 delegates through both the early states and Tuesday's contests, a tiny fraction of the number that Biden and Sanders added to their hauls.

Biden's strong performances on Tuesday, when he won at least nine of the 15 contests up for grabs, has catapulted him to a commanding lead in the race. He will claim at least 453 delegates, more than Sanders's 382 delegates, with votes still to be counted and delegates still to be allocated in states like California and Texas.