The congresswoman was asked the question as she was leaving a closed-door meeting in the House basement Wednesday morning.
Other congressional Democrats have balked at the idea of Sanders, a longtime independent and self-proclaimed democratic socialist, being the party's nominee in the general election.
"Look, the bottom line is very simple," Schumer said Tuesday when asked about Sanders's praise of former Cuban leader Fidel Castro's literacy program.
Sanders has surged to front-runner status after virtually tying for first in Iowa and winning New Hampshire and Nevada outright.
In the latest NBC News-Marist poll, Biden held a 27 percent-23 percent lead over Sanders in South Carolina.
Biden's candidacy could see new momentum after receiving the significant endorsement of House Majority Whip James Clyburn (D-S.C.) on Wednesday morning.
Clyburn is the highest-ranking black congressional lawmaker and Biden has held a firm lead on support from black voters. »