The senators sent the request to Biden in a letter obtained by the Associated Press. Sens. Claire McCaskill of Missouri, Jon Tester of Montana, Sherrod Brown of Ohio and Bill Nelson of Florida signed it along with Cardin.
They note Biden has made progress in negotiations on spending and deficit reduction and say that as talks move forward the vice president must insist that significant changes to Medicare remain off the table.
All five senators are from states with significant numbers of elderly voters and all are up for reelection in 2012.