For conservatives who refuse to fall in line behind Donald Trump as he marches toward the Republican presidential nomination, there's only one option left: resistance.

I've argued before that resisting Trump should take the form of a third-party bid, because it's the honorable thing to do, it's politically smart, and it will show that the Republican Party can't win without true conservatives. But the question remains: Who should be the standard-bearer of this party?

Nikki Haley would be the perfect choice, but it seems that, tragically and short-sightedly, she's backing Trump, however tepidly.

Mitt Romney almost certainly won't. And that's okay — while he's a good man, he also represents the self-delusion of the GOP establishment that made Trump's rise possible to begin with.

Paul Ryan is a good choice. He represents much of what's best about the Republican Party, he gets it, and he has experience with a national campaign. But he ruled himself out of running for president. Technically, he ruled himself out as a white-horse candidate in a contested convention, not a third-party campaign, but it sounds like he's determined to stay in the speaker's office.

But then there's somebody else. Somebody who has quickly grown to become a hero for conservatives. I am speaking, of course, of the freshman senator from Nebraska, Ben Sasse. He basically sounds like a hero made for conservatives like me. He's one of those Tea-Party-wave senators and a serious conservative, but also an intellectual, with a PhD from Yale, who was a college president before going into politics, who can explain conservatism in 90 seconds. He sent his teen daughter to work on a farm one summer to learn about life. He just seems like a swell guy, and not just because he's great at Twitter.

As best as I can tell, he's the highest ranking Republican official to say in no uncertain terms that he won't support Trump and to call for a third-party candidacy. In a poignant and powerful letter posted on Facebook, he wrote:

With Clinton and Trump, the fix is in. Heads, they win; tails, you lose. Why are we confined to these two terrible options? This is America. If both choices stink, we reject them and go bigger. That's what we do. Remember: Our Founders didn't want entrenched political parties. So why should we accept this terrible choice? So... let's have a thought experiment for a few weeks: Why shouldn't America draft an honest leader who will focus on 70 percent solutions for the next four years? You know... an adult? [Ben Sasse]

He immediately added a phrase that was clearly meant to emphatically state that he doesn't want to be that third-party candidate while leaving him some wiggle room: "Such a leader should be able to campaign 24/7 for the next six months. Therefore he/she likely can't be an engaged parent with little kids." Don't look at me!

Come on, senator. As Bill Kristol immediately pointed out, little kids would love the campaign. They'd be homeschooled and they'd get to travel the country. It would be a great experience for them — it's actually an argument for running.

Sen. Sasse has all the requisite qualities and more to be this third-party candidate. Draft Ben Sasse!