Massachusetts Democrats changed the rules of the game after Ted Kennedy’s death, granting to Democratic governor Deval Patrick the power to appoint an interim senator pending today’s special election — a power that it had expressly denied to Republican governor Mit Romney in the 2004 election cycle. The reason was to maintain the 60th vote on the president’s health-care legislation and cement Ted Kennedy’s “legacy.” The plan didn’t work on that front, since Democrats couldn’t come to an agreement on the specifics of the bill in the time allotted. And the political maneuvering in the State legislature had enormous political ramifications, feeding a sense of foul play by the Democratic establishment. As much as anything, this unfair play helped propel Scott Brown to a competitive position — and he and Martha Coakley have done the rest. We’ll find out tonight whether Brown will succeed, but you have to wonder whether some state Democrats are second-guessing their decision to change the rules of the game after Kennedy’s death.