States Have Rights Too!

It never ceases to amaze me the hypocracy of the Replublican Party. And Bush's recent support of a national gay-marriage ban (actually, a frigg'n constitutional ammendment!) is testament to the fact that Republican's are all for smaller government, and less government involvement in an individuals' personal affairs in so far as it you are reducing the government's involvement in one's finances, and not say, who I chose to partner with to raise a family...
To be completely fair, I can see the jurisdiction of the federal government in regards to civil unions, considering the fact that according to our constitution, a union in one state must be honored by all the other states. So it is not as simple as leaving it up to the states to decide for themselves. But if states are allowed to decide for themselves is sodomy is legal or illegal, shouldn't they aslo be allowed to decide for themselves what constitutes a legal marriage?