“Why should I watch a fourth debate with these losers?” you’re asking yourself. “I’ve seen this show three times already.” Eh, not really. Not like this. Nate Silver ably summarizes how much has changed for all three members of the top tier since the last debate in September:

I'm looking forward to tonight's debate more than some of the previous ones because each of the top 3 candidates is dealing with something new:
Warren: 1st debate as the perceived frontrunner
Biden: 1st debate since Ukraine
Sanders: 1st since heart attackhttps://t.co/q5sgzpwjBp

— Nate Silver (@NateSilver538) October 15, 2019

The news cycle will intrude tonight on the usual oneupsmanship over who can offer the most free sh*t. There’s impeachment and Ukraine, of course, and all of its attendant questions: Should House Democrats vote to formally open an impeachment inquiry? Should they in fact impeach the president based on the facts already known to us? Should they throw Rudy Giuliani in a makeshift congressional brig for contempt? But there’s much more going on besides impeachment:

"It's important to remember just how much has happened since the last debate 33 days ago." @BriKeilarCNN catches us up in 32 seconds here pic.twitter.com/LZHXPwZUKE

— Brian Stelter (@brianstelter) October 15, 2019

There’s Trump’s decision to stand down amid a Turkish onslaught against the Kurds, an uncomfortable predicament for a field of candidates that’s duty-bound to oppose him on everything on the one hand but on the other hand likes to present itself as the peace-loving alternative to GOP warmongering. How hard do they want to hit Trump for *not* leaving American troops in harm’s way?

Lesser topics may assert themselves too. Where do our candidates stand on the NBA’s stance towards China? The world’s wokest professional sports league is a natural ally of the Democratic Party; do the Democratic candidates want to jeopardize that alliance with harsh criticism?

How much abuse will Beto O’Rourke take from the competition for his recent insane demand that we strip charities that oppose gay marriage of their tax exemption? Pete Buttigieg in particular has been critical of O’Rourke, eager to use the issue to signal to wavering Biden voters that he’s a “moderate” alternative. Will the left-wing candidates like Warren and Sanders, whose fans might like the idea of punishing dissidents who oppose some LGBT rights, go after Beto?

And what about the feud between Kamala Harris and Tulsi Gabbard, who missed the third debate but returns tonight? They’re both basically asterisk candidates at this point but Harris owes Gabbard payback for wrecking her at the second debate over her record as California AG. Maybe she’ll come after her for her foot-dragging on impeachment, assuming she doesn’t spend every moment this evening trying to claw back into the top tier by attacking Elizabeth Warren. As for whom Gabbard will target, it’s anyone’s guess. She’s criticized Trump harshly for his decision in Syria. Maybe she’ll focus on him tonight in hopes of ingratiating herself to left-wing voters instead of the righties who like her but would never vote for her over Trump.

There will of course also be an awkward question for Joe Biden about what exactly Hunter Biden was doing sitting on the board of a Ukrainian company whose field he had no expertise in. Democratic strategists have spent the day wondering what the hell Hunter was doing inserting himself into the news cycle this morning on the very day of a Democratic debate, all but inviting dad’s competition to attack him about it tonight:

“Everyone else had laid off of Joe Biden,” the senior adviser added. “Now that’s all gone. I would bet $100 it’s the first question. If it is, it’s a major disaster.”

“Why even put it out there to answer for that?,” another rival campaign aide asked. “Now it’s fair game that a moderator can bring it up.”

A third aide wondered why the whole thing was necessary at all: “When I saw that I thought, why would you do that? There was no clamor to hear from Hunter directly.”

That may be the single greatest source of suspense tonight. Will anyone onstage dare align themselves with Trump by attacking Biden aggressively for serving as the Obama White House’s point man on Ukraine while Hunter Biden had business interests there? If you’re Amy Klobuchar or Cory Booker or Tulsi Gabbard, what do you have to lose?

The debate will air on CNN and all of its online platforms from 8 p.m. ET to 11 p.m. (It’ll also stream on the homepage of the New York Times, which is sponsoring the debate.) There are, by the way, no fewer than 12 candidates onstage tonight, which I believe is the largest number yet to share a single stage this year — a weird detail at a moment when the field of credible candidates is supposed to be shrinking. The October debate featured just 10 candidates, but since the DNC imposed the same qualifying requirements for this one as for that one, both Gabbard and Tom Steyer were able to make the cut in the interim. When are we going to get a debate between the top three and maybe Buttigieg and Harris, the only five candidates with even a remote chance at the nomination? It’ll have to wait for next month, if not later. But it’s coming. This evening is probably the last chance for a breakthrough for everyone except those five.