This year the primary election process seems to have taken on much more of a "my guy or nothing" attitude among many voters. We've seen that for several cycles with the Ron Paul nuts, but increasingly that seems to be the theme of the day with other campaigns as well. The Romney forces say they can't support Newt if he wins, and the Newt forces say they'd rather elect Obama than Mitt. Rick Santorum seems to be the only guy who has escaped these personality cult politics, but that's probably because he has relatively few followers.
It used to be GOP voters would shrug their shoulders, swallow hard, and go vote for the RINO-of-the-day who was foisted on them by the party establishment. That all changed when the Tea Party came along and supported candidates who were in some cases unelectable (like Christine O'Donnell and Sharron Angle) rather than line up behind a unreliable RINO. As a result we probably gave away the Senate seat in Connecticut and our best chance to flush Harry Reid away in Nevada. There were victories, like Marco Rubio in Florida, but demanding ideological purity is a risky game.
So, what happens with Tea Party voters if Mitt Romney wins the nomination? Do they stay home and help give Obama four more years, or so they swallow their pride one more time and pull the lever for Mitt? It all comes down to priorities, and the first priority has got to be ending the reign of Obama. As bad as Mitt might be on some issues, is he really going to be worse than Obama? Of course not.
Some are saying they're okay with electing Obama as long as the GOP holds the House and takes the Senate (the latter is certainly not a sure thing). However, that ignores the fact that Obama has already shown he's willing to exert power that he may not even legally have via unilateral executive orders and the like. He recently made two recess appointments even though Congress wasn't in recess. If you think you can check his power with a GOP congress, you're wrong. You can stop legislation, but you can't stop executive orders and onerous regulations that will be imposed by Obama's appointees.
Bottom line, whoever the nominee ends up being the fate of the nation requires the allegiance of ALL GOP voters toward our candidate. We may not like him all that much, and he probably won't be our favorite, but if he can win and stop Obama we must support him.