There are other options, such as the Constitution Party. Yes, I'm aware of the usual objections to voting third-party, but I can tell you one thing - nothing's better at grabbing the GOP's attention.
Setting yourself on fire will also grab attention -- until the fire runs out of fuel and dies. At that point, what's left has about as much substance as any third party.
How about someone taking Hagel on in a primary? That's a far better option than helping a RAT by voting Constitution Party. They're only there to raise money. They make no positive difference at all.