Maine Democrats handed progressive firebrand Graham Platner an easy win in Tuesday's Senate primary, looking past his personal scandals in hopes he can oust five-term GOP Sen. Susan Collins in November. Why it matters: Tuesday's results set up what's sure to be a nasty, expensive battle for a seat that will go a long way toward determining control of the Senate. They also illustrated the huge contrasts now animating the political parties: GOP voters are almost always in lockstep with the leader