(Updated 12:15 p.m. 3/11)

When Sen. Rand Paul tied the Senate up in knots for a day last week to make a point about the Obama administration's controversial use of drones to assassinate enemies of the U.S., the libertarian Kentucky Republican was hitting on one of those rare issues that unites activists on the political left and right.

Evidence came when veteran Rep. John Conyers, who ranks as one of the most liberal Democrats in the House, tweeted out a "you go" about the Paul filibuster. The 83-year-old Detroit lawmaker was sufficiently hip to use ...