Georgia’s presidential primary is here, and a large GOP field is down to three legitimate candidates: Ted Cruz, John Kasich and Marco Rubio.

Why didn’t I mention the front-runner, Donald Trump? Because, for me, the race is down to one question: Who can beat Trump now and Hillary Clinton later?

The answer, for me, is Marco Rubio. I will happily vote for him Tuesday in the hope he can derail Trump and defeat Hillary.

Like Rubio, Cruz and Kasich are conservatives who, I am convinced, would govern conservatively. I would count on any of them to push the right priorities as president (although I question Cruz’s ability to deliver those priorities, given his track record in the Senate).

But the calculus for me is this: I think Cruz could beat Trump but not Clinton. I think Kasich could beat Clinton but not Trump. I think Rubio could beat both. This year, that’s all I need.

For a conservative, beating Clinton is an obvious enough priority. But let me explain why defeating Trump is so important.

Trump leads the pack for several reasons, but these two strike me as paramount: He speaks to issues that deeply affect a large segment of the population but which Republicans have ignored or paid lip service for a long time, and he has seized on the real, justified anger many Americans have toward a rotten governing class.

The GOP has no excuse. Conservative thinkers have spent a great deal of time crafting policy ideas that are pro-work, pro-family and would benefit the same people gravitating to Trump. But too few elected Republicans have pursued these ideas. You can blame the fact a Democrat is president, but congressional Republicans have not so much as sent such measures to Barack Obama’s desk.

That said, Trump has shown no sign of embracing these — or even un-conservative — policies. He has shown no sign he actually knows how to solve these problems.

He has built his campaign on a foundation of real problems, but the rest of the edifice consists of exaggerations, outright falsehoods and scapegoats, topped with his name in gold plating as if that’s a plan. No explaining what he would do or how he’d do it. This is akin to the blueprint past demagogues and charlatans have used, often to tragic effect.

If Trump built his casinos and condos so recklessly, he’d never get a permit to open them — unless he called in favors from politicians to whom he’d donated. Which he has, more generally, admitted doing over the years. Which means he’s been fouling the very stables he now says he’d clean out.

If you find yourself rebelling against the rotten establishment, you might ask yourself why Trump spent so much of his life contributing to the rot. And why he’d change now.

By contrast, Cruz and Rubio weren’t even in Washington six years ago and won their seats by battling against the same-old, hand-picked establishment types. The notion either man has been part of this long-growing problem, to even a fraction of the extent Trump has, is absurd.

So, stopping Trump is critical if you really want to fix what ails Washington. The evidence to date suggests Rubio is better-positioned than Cruz to do that. If he can, he is clearly better-positioned than Cruz to win in November. In a campaign defined by the notion America needs to win again, Rubio is the best shot we have at a winner.