Ron Paul is in almost complete agreement with Kucinich's policies on war, the military-industrial complex, and civil liberties. Kucinich himself has said that if he were the nominee he would choose Ron Paul as his running mate. He and Ron Paul work together commonly on the floor of the house of representatives, and often vote together as the only dissenting votes on insidious legislation such as the "Homegrown Terrorism Prevention Act". It may be hard for Kucinich supporters to put aside partisanship and register to vote Republican, if only for a month or two, but if you are still committed to supporting an anti-war, pro-peace candidate who has a consistent record of voting against war-funding, then Ron Paul is now your only choice other than Mike Gravel.
Progressives have a difficult choice to make here: we can give in to group-think and vote in the Democratic party primary because when it comes down to it party loyalty is more important than issues; we can bow out of the primary process altogether and start working for the green-party presidential run in 2008; or we can take the time to help the only viable peace candidate, Ron Paul, get some more delegates in our respective states so that he can have some sway in the brokered convention that the Republican party is headed for. Voting for Ron Paul in the primaries doesn't prevent you from voting for the Democratic or Green Party nominee in November. Think of it as an extra chance to dissent and vote for peace before the nation holds its collective nose in November and votes in another corporate candidate.