The three most important states Tuesday night were always going to be Florida, Ohio, and North Carolina, for the simple reason that they’re swing states, while the other two (Illinois and Missouri) are not. So the person who won the swing states is swingin’ easy, and tonight, that person is Hillary Clinton.

Winning Florida the way she apparently has, by two-to-one, says, “I can win Florida this fall,” and it says it with an exclamation point. The outcome was called the moment all the state’s polls closed. Ditto North Carolina—hey, the polls were actually right!—which is of course a red state in its internal politics but which, on the presidential level, can go blue, as it did in 2008, if the voter mix is favorable. And winning North Carolina in a rout also announces, “I will compete here this fall.”

But winning Ohio the way Clinton has is the thing that seals it. The state was called at 8:42 p.m., just more than an hour after the polls closed. Everyone, I mean everyone, expected a nail-biter in the Buckeye State, after Michigan. Yes, she was ahead in the polls: +5, +8, +this, +that. But she was +20 in Michigan. So what did +8 mean?

Well, it turned out to be about right. If it had been wrong—if Bernie Sanders had won Ohio—we’d be in a completely different world. He could have continued to dismiss her wins as Dixie aberrations, and he could have combined Michigan and Ohio into a narrative. Now, it looks like it’s Michigan that’s the aberration.

Clinton should of course celebrate, but she should learn this from these last two weeks. She’s vulnerable in the Rust Belt states. The trade argument hurt her, and she’ll need a better answer. It’s been a tight squeeze. Wisconsin is April 5, New York is April 19, and Pennsylvania is April 26. She needs to win all those, and the key thing is that she needs to win them in a fashion that reassures Democrats, “okay, she’ll hold those states down, Trump can’t change the map.” Sanders is going to win some meaningless caucuses in the meantime, in red states that neither he nor Clinton could win in November in a jillion years, and he’ll pick up some delegates doing it, but she just needs to keep the focus on the important states and make sure she racks up convincing margins there. Which doesn’t mean coasting—it means keep thinking of new positions to take.

I’m surprised Clinton did as well as she did tonight in part because she’s kind of gotten away from the message that drove her campaign last year when it started. The middle class needs a fair shake, was the original message. Now it’s a little different, that every person should be able to fulfill his or her potential. That’s nice, but it seems a little abstract. Everybody thinks of themselves as middle class, so if you mention middle class, it’s hard for me to see how that goes wrong.

The question now is what Sanders does. How nuclear negative does he go? Because both these campaigns, his and hers, have plans laid out about how deep they’d need to go into X kind of attack if they got Y number of votes and delegates behind. Those are theoretical plan when they’re drawn up. But now, Sanders is at that point. So far, most of his hits on her have been more or less fair; they’ve mostly been primary hits, as opposed to general election hits.

General election hits on Clinton would be: the emails, Whitewater, integrity, all that. The thing to keep an eye on now is whether Sanders goes there. If Clinton had lost Ohio, I’d have told you to watch for whether Clinton started lambasting Sanders on the tax increases implied by his plans. She’s not going to have to go there now, which will help her a lot in terms of persuading Bern-feelers eventually that they will need to live with her.

But will Sanders start attacking Clinton in ways that Republicans would? That is the question that emerges from tonight’s results. Up next is Arizona. It’s not a natural Sanders state. Latinos and alter kockers. Clinton people, by and large. If he slings mud here, it’s a sign of, well, let’s just say refusal to accept. What he ought to do is keep campaigning vigorously, but without any of that anti-Rahm Emanuel tincture he brought to the Illinois race.

Sanders can’t win the delegate race now. What he can win is the contest to influence the direction of the Democratic Party. That’s what he can deliver for his millions of supporters, and if he does anything else, we’ll learn something about him.