As one who feels like an increasing number of progressives, I won't vote for a conservative, but I see no reason to vote conservative lite just to keep a conservative out of office. I'd rather support a true progressive, even if it means a conservative will win. The Democratic party needs to learn that nominating candidates who tack left in the primary but will tack right in the general and govern from a conservative lite position, is a sure way to lose elections, and that isn't going to happen as long as the left keeps falling for the "lessor of two evils" argument. Sure a Democratic candidate gets elected but if that Democratic representative mostly represents corporatist conservative lite positions what difference does the letter by their name make? It's like playing poker for matchsticks, wins and loses are part of a game with no real meaning or consequences. The only way to get people really involved in politics is to let them see that there are real consequences to choosing who you vote for in elections.
This worries the heck out of me. If your approach is common enough, the GOP will be running its collective hands in glee safe in the knowledge that there will be a GOP President in office until there are enough progressives to carry the election - which may never happen.
As wareyin points out, the repercussions could last for decades if conservative Christians hold the majority on the supreme court.