Michael Bloomberg’s campaign publicly postures that Bloomberg is in a two-man race for the Democratic presidential nomination, but it is worried about Bernie Sanders sweeping up enough delegates to be unstoppable unless centrist rivals bow out.

An internal campaign memo between top Bloomberg aides dated Feb. 17 warns that any “serious delegate advantage” from the Super Tuesday primary contests on March 3 is likely to be maintained, and as the field stands now, the Vermont senator is set to hold a 400-delegate lead over second-place Bloomberg after Super Tuesday, with the bulk of remaining delegates spread across Bloomberg and the other centrist candidates: former Vice President Joe Biden, Sen. Amy Klobuchar of Minnesota, and former South Bend, Indiana, Mayor Pete Buttigieg.