How often do you see a Senate race where there’s a compelling argument that each of three different candidates is going to win?

Typically there’s one or even two who seem likely to prevail plus a dark horse who can’t be written off. That’s what happened in Ohio a few weeks ago. J.D. Vance had Trump’s backing and looked to be a solid favorite but Josh Mandel had Ted Cruz and the Club for Growth in his corner. And Matt Dolan had an outside chance of sneaking up the middle by consolidating the less MAGA wing of the Ohio GOP electorate.

Vance won, of course. Dolan didn’t really threaten him in the end.

The situation in Pennsylvania is different, a true jump ball. I can give you a persuasive theory for why any of the top three are poised to pull it out tomorrow night. Here’s where things stand at the moment according to Emerson:

Lotta undecideds there. And the Sands and Bartos supporters might switch in the final hours as they accept that their candidates are also-rans.

So, theories. Why is Oz going to win? That’s easy — he’s the candidate of Trump and Trump continues to have major sway over Republican voters. He rescued Vance from fourth place in Ohio; there’s no reason to think he can’t drag Oz over the finish line in Pennsylvania. Oz also enjoys high name recognition due to his television celebrity, has spent millions on ads, and has had Sean Hannity pushing him on Fox viewers for months. It’s easy to imagine the eleventh-hour Trump/Hannity attacks on Barnette, that she’s unvetted and can’t win the general election, tilting a few decisive votes into Oz’s column in the end.

Why is Barnette going to win? That’s also easy — momentum, momentum, momentum. She was the big gainer in Emerson’s polling since last month, picking up 12 points. She now leads McCormick in multiple polls. There’s a sense that she’s gathering force as undecideds who prefer her on the merits but had written her off as a no-hoper finally swing behind her now that they realize she has a chance to win. More importantly, Barnette has what Oz and McCormick each sorely lack, arguably the essential credential in any Republican primary: Authenticity. She’s a true populist, unlike the rich-guy pretenders. And as a proud black conservative, nominating her would give Pennsylvania Republicans a chance to stick it to liberals who are forever calling them racists.

Why is McCormick going to win? That’s … a little harder. He’s landed in third place in each of the last three polls and was brutalized by Trump from the stage during Trump’s rally with Oz last week.

But you don’t have to squint hard to see how McCormick pulls it off. Read the fine print in Emerson’s poll:

While Oz holds a plurality of support in the primary, 48% of Republican primary voters have a somewhat or strongly unfavorable opinion of Oz, compared to 32% who have an unfavorable opinion of McCormick and 28% who view Barnette unfavorably. David McCormick has the highest favorability: 46% have a strongly or somewhat favorable opinion of McCormick. Barnette holds 43% favorability while Oz holds 37%.

McCormick may end up as the compromise option in the race for undecideds who are torn between Oz and Barnette. Is McCormick endorsed by Trump? No — but he seems more sincerely conservative than Trump’s candidate, the celebrity squish Oz. Is McCormick an authentic populist? No — but as an electable mainstream rich guy, he’s certainly more likely to win the general election than Barnette is. Especially if stuff like this keeps getting dropped on her:

NEW: @NBCNews has verified these images of Barnette marching toward the Capitol on Jan 6 alongside member of the Proud Boys who were later arrested and indicted for breaking into the building and attacking officers. 1/4 pic.twitter.com/CzGgLOhQWn

— Dasha Burns (@DashaBurns) May 16, 2022

That comes a day after Barnette dismissed her old anti-Islamic tweets as no big deal because they’re “not even full thoughts.” I’m sure most Pennsylvania Republicans would prefer a nominee whom they regard as “one of us” and who they believe will present a formidable challenge to John Fetterman in the fall. But if they’re now convinced that there’s no such candidate in the race, they may opt for the middle-ground choice — McCormick, the guy who’s not a RINO and who also isn’t going to make swing voters wonder if he was inside the Capitol smashing things up on January 6.

Salena Zito is covering the race in Pennsylvania and also thinks there could be late movement towards McCormick:

In events across the state, in dozens of counties in the closing days of the campaign, voters at McCormick events, mostly suburban women, told the same story of being drawn to Barnette’s performance at the Grove City event two weeks ago. But some of them have hit the brakes on Barnette as she struggles to set people straight on her resume…

Polling conducted by Mark Harris, who runs an outside group supporting the campaign, showed McCormick ahead by 1 percentage point over Barnette, followed by Oz. Two days earlier, she had surged ahead of both. But she has since failed to confirm the stories she has told of her life experiences. She has also claimed to a reporter that tweets from her personal account weren’t hers. Then she closed her Saturday rally to the journalists assigned to cover her final events — the opposite of what Trump did during his campaigns, when he welcomed but also liberally bashed the media.

Ironically, if McCormick does pull it out, I wonder if he’ll have his frenemy Trump to thank. Oz may be too much of a squish for MAGA fans to support even with Trump’s backing, but Trump’s attack on Barnette a few days ago, alleging that she has no chance in the general election, may have given pause to anti-Oz undecideds who are trying to choose between Barnette and McCormick. How many Republicans were tilting towards Barnette, heard Trump say that they’ll be forfeiting the seat to Democrats if they support her, and are now leaning McCormick as a result?

We’ll know in 36 hours. I’ll leave you with this, another not-so-great sign for Oz.

NBC News poll asks Republicans: 'Do you consider yourself to be more of a supporter of Donald Trump or more of a supporter of the Republican Party? Result: 34 percent Trump, 58 percent GOP. 34 is lowest ever; 58 is highest ever. https://t.co/UngjOYtAJx pic.twitter.com/zqSHz8b3eG

— Byron York (@ByronYork) May 15, 2022