Sen. Dianne Feinstein (D-Calif.) said Wednesday that she is “undecided” about removing the Senate’s filibuster rule. Feinstein, 87, the oldest senator, told reporters on Capitol Hill that she has concerns that eliminating the legislative filibuster—which requires a threshold of 60 votes to pass major legislation—could backfire on Democrats when Republicans are back in the majority. “I would say I’m undecided,” Feinstein said. A future Republican majority “is a factor, one of the reasons why I’m hesitant,” she said. The filibuster rule was originally adopted to give the minority party a stronger voice in the Senate and prevent partisan control of the upper chamber by the majority. The rule essentially requires a super-majority threshold, now at 60 votes, to cut off debate in the Senate and bring legislative bills or other measures to a vote. While a number of Democrats, such as moderate Sen. Joe Manchin (D-W.Va.), favor keeping the legislative filibuster …