There’s a simple metric you can use to evaluate whether Donald Trump can beat Hillary Clinton in November. That is this: Is he going to win a state that Mitt Romney lost? If the answer to that question is no, then Trump cannot win the presidency for the simple reason that he can’t win enough electoral votes to get across the finish line.

If you play around with our electoral map tool, you can see that most of the states we generally talk about as swing states are ones that President Obama won in 2012: Ohio, Pennsylvania, Virginia, Florida. An exception is North Carolina, which Romney won.

If the map doesn’t change from 2012, this is what 2016 would look like.

At the moment, Trump leads in none of those five states, according to the RealClearPolitics averages. He basically has to win at least three of them to win the election. If he loses North Carolina, the door is all but shut.

But! But! Even after a miserable two weeks of polling, there’s a faint glimmer of hope that Trump could win one state that Romney lost four years ago: Iowa.

Iowa has gotten closer over the past month and a half, in the very few polls conducted in the state. Trump and Clinton are now basically tied, which is a better position than Trump enjoys in most places.

That narrow margin is thanks to a new survey from Suffolk University, giving Trump a one-point lead in the state, 41 to 40. Part of that is because the poll sampled likely voters, a group that leans more Republican. Part of it, too, is likely that Iowa is one of the whitest states in the country, and Trump tends to have an advantage among white voters.

But part of it, too, is that Suffolk found some significant Bernie Sanders holdouts in the voter pool.

Here are Suffolk’s results, broken out by demographic.

Let’s walk through this.

Clinton trails by one, in part because Trump has a slight lead with independents — and because each candidate gets 80 percent of the vote from members of their own parties. We noted last week that Trump’s softness in recent polling was a function of his getting less support from Republicans than Clinton got from Democrats. Here, both are doing fairly poorly, and they’re tied.

Why? Well, 97 percent of voters who told Suffolk that they had backed Clinton at the state’s caucuses said they would support her in November. But only 68 percent of those who had backed Sanders had the same intention. A quarter of Sanders backers said they hadn’t yet made up their minds.

The breakdown by age reinforces that idea. Younger voters, who heavily favored Sanders in the caucuses, are much more undecided than older ones. This is a group that Democrats usually have little trouble winning — but Clinton is having some trouble here.

Despite all of that — Sanders holdouts, a likely-voter screen — Clinton is still tied. But unlike in most other recent polls, she’s not leading in the state.

So that’s the glimmer of hope for Trump: Maybe he can pick up a state that Romney lost. If he does, and nothing else changes?

He would lose by slightly less than Mitt Romney did.