Mr. Lau argued no candidate has shown an ability to coalesce the party behind them and he predicted that Ms. Warren, who has been pitching herself as the “unity” candidate for weeks, would prove “the consensus choice of the widest coalition of Democrats in every corner of the country” by March 3, Super Tuesday.

The memo provides, by far, the most detailed projections released by any campaign of delegate viability heading into Super Tuesday, predicting a “three-way race” between herself, Mr. Biden, the former vice president and Mr. Sanders, the Vermont senator. She omits Mr. Buttigieg, the former mayor of South Bend, Ind., even though he received more support than her in Iowa and could do so again in New Hampshire. Candidates need to reach 15 percent support in each congressional district to win delegates, as well as statewide for statewide delegates.

“If the early states deliver mixed results for the field, and no seismic event shakes up the top three, the remaining viable candidates for the Democratic nomination as of Super Tuesday will be Joe Biden, Bernie Sanders, and Elizabeth Warren,” the memo predicts.

Of Mr. Buttigieg, the memo says, “Despite being in the race for a year and effectively tied for second in Iowa, Pete Buttigieg fails to break the 15 percent threshold in any of the Super Tuesday states and is in danger of getting locked out of critical statewide delegates entirely.”

The memo goes on to foresee struggles for Mr. Buttigieg in more diverse states: “He still hasn’t answered tough questions about his record in South Bend.”

The Warren memo said their “internal projections” show that of the 165 congressional districts that will vote on Super Tuesday, Mr. Sanders and Mr. Biden would currently finish above the 15 percent threshold in 98 percent and 96 percent of them, respectively.

Ms. Warren is above that delegate threshold in 65 percent of the districts, the next most.

There is then a big drop-off to Mr. Bloomberg (delegate-eligible in 15 percent of districts), Mr. Buttigieg (6 percent), and Senator Amy Klobuchar (5 percent, which is entirely in her home state of Minnesota), according to the projections.