Cheer them on to their rivals...

Kos addresses the issue of myopia within the Democratic Party. From time to time, the folks over at NARAL and NOW do have a myopic vision of what their ideal candidate should be. There are good Democrats out there who just happen to be against abortion. Harry Reid is a pro-life Democrat that voted AGAINST the confirmation of John Roberts. What more can we ask for?

The Choice groups aren't the Democratic Party. The Democratic Party is the Democratic Party. If NARAL and NOW aren't pleased with Casey or Langevin or whoever, they don't need to endorse. There are plenty of pro-Choice Democrats that could use their help. Same goes for the environmental, labor, trial lawyer, etc groups.
As Reid's votes on virulently anti-choice (and anti-labor, anti-environment) judges shows, it's better to have a Democrat than a Republican hold any seat in Congress. Better, that is, for those of us who care about the broad palette of progressive issues. That doesn't mean that NARAL is forced to support Casey. Neutrality is an option.