Another piece of the Democrats’ agenda went down in flames Tuesday when Senate Republicans united to filibuster campaign-finance-reform legislation. In the face of GOP obstructionism, should the Democrats consider losing the filibuster altogether? Ezra Klein lays out how they can do so with only 51 votes: The Constitution requires the Senate to “determine the Rules of its Proceedings” at the opening of each session. That means, assuming the Democrats still control the Senate next year, they could declare the filibuster out-of-bounds—and the GOP couldn’t filibuster the elimination of the filibuster, since doing so would prevent the Senate from considering its own rules and would therefore be unconstitutional. This step has never been taken before by the Senate, though it was frequently discussed in the 1950s, 1960s, and 1970s.