Why I am not a Republican:

They are bald-faced liars, pretending to espouse Federalism, when they actually hate the concept. That doesn't make them worse than Democrats, but they aren't a lot better. And why would one relish the idea of liars telling you what to do, for your own good?

David Boaz of the Cato Institute has decent summary:

President Bush's No Child Left Behind Act establishes national education testing standards and makes every local school district accountable to federal bureaucrats in Washington.

President Bush and conservative Republicans have been trying to restrain lawsuit abuse by allowing class-action suits to be moved from state to federal courts. The 2002 election law imposed national standards on the states in such areas as registration and provisional balloting. A 2004 law established federal standards for state-issued driver's licenses and personal identification cards.

President Bush's "Project Safe Neighborhoods" transfers the prosecution of gun crimes from states to the federal government. The administration is trying to persuade federal courts to block implementation of state initiatives on medical marijuana in California and assisted suicide in Oregon.

Perhaps most notoriously, President Bush and conservatives are pushing for a constitutional amendment to ban gay marriage in all 50 states. They talk about runaway judges and democratic decision-making, but their amendment would forbid the people of New York, Massachusetts, Connecticut, California or any other state from deciding to allow same-sex marriage. Marriage law has always been a matter for the states. We should not impose one uniform marriage law on what conservatives used to call "the sovereign states."