Voters have made up their minds about Trump. They’re still uncertain about Harris.

WASHINGTON — “Who’s going to win?”

Anyone who writes about politics hears that question constantly. Let’s get it out of the way first: I don’t know; neither does anyone else.

With the campaign now in its final stretch, Vice President Kamala Harris holds a small lead over former President Donald Trump in most national polls (47%-44% in the average by pollster FiveThirtyEight.com). She also holds small leads in two of the seven swing states, Wisconsin and Michigan, while in the remaining five, neither candidate has a consistent edge.

Two leading models that attempt to forecast the election disagree, with the Economist giving Harris the slightest of edges, while Nate Silver’s Silver Bulletin leans ever so slightly toward Trump.

The models are extremely sophisticated and good at what they do. But the polls on which they’re built historically have been wrong by a few points. While they underestimated Trump’s support in 2016 and 2020, they underestimated Democratic support in 2012. We can assume there probably will be polling errors this year, but we can’t know either the size or the direction in advance.

Moreover, all election models are built on a relatively thin foundation.

A person who wants to bet on the outcome of a baseball game can draw on data from more than 238,000 major league contests over the last century and a half. By contrast, the U.S. has held only 19 presidential elections since widespread polling started to provide somewhat reliable data. There’s only so much information to be gleaned from so small a sample.

What we can know are some of the key dynamics that will shape the race as both campaigns prepare for next week’s scheduled debate.

It’s all about Harris

Defining Harris remains key for both sides.

So far, the vice president has done well. Her standing with voters has improved since President Joe Biden dropped out of the race in July, despite steady Republican attacks. The share with a favorable view of her, 48%, is notably higher than 42% with a favorable view of Trump, the latest YouGov/Economist poll found.

She’s also closed the gap with Trump on some key measures. The YouGov poll found, for example, that almost the same share of voters see both candidates as strong leaders — 51% for Harris, 53% Trump.

The race has been reshaped since Biden dropped out. The shifts have not involved Trump’s support declining; rather, Harris has picked up backing, primarily from voters who were flirting with a third party or from the previously undecided.

That shouldn’t be a surprise.

Trump’s vote is a marvel of consistency: He won 46% in 2016, 47% in 2020, and if you take the current average from poll firm FiveThirtyEight and leave out the undecideds, he’s right at the same range again.

Americans know what they think about the former president, who was among the country’s most recognizable figures for years before he entered elective politics a decade ago.

Democrats have tried to make the case that Trump has deteriorated mentally and would be more dangerous as president now than he was before. But after four years of his presidency, two previous campaigns, the Jan. 6 attack on the Capitol, multiple indictments and one conviction, there’s very little likelihood that new information will change many minds about him.

Harris is not exactly a newcomer. But the vice presidency isn’t a job that attracts a lot of attention from most voters, nor one that allows its occupant to set out her own priorities. So a significant share of voters still have questions about who Harris is and what she stands for.

The YouGov/Economist poll underscores that point: 36% of U.S. adults said they wanted to see or hear more about Harris, the poll found. Only 22% said they wanted to hear or see more about Trump.

Among Latinos, a group that includes a disproportionate share of swing voters, 46% said they wanted to hear more about Harris, compared with 14% who wanted to hear more about Trump.

That’s why the Sept. 10 debate could be so significant — it’s an event that a huge share of voters will see or hear about.

And for all the attention to whether the candidates’ microphones will be on or off when the other is speaking or what wild attack Trump may make, the undecided voters will mostly be paying attention to who Harris is and what she stands for.

Where Harris still comes up short

Harris has regained much of the support that Biden had lost among young people and Latino and Black voters. But in most polls, her backing still remains somewhat below the marks that President Barack Obama hit in 2008 and 2012, or that Biden achieved in 2020.

Two factors drive that underperformance.

A number of polls continue to show Trump doing significantly better with Black and Latino voters, especially younger men, than other recent Republican nominees have done.

Whether that’s real or not has been hotly debated — subsamples of general election polls can be misleading, and not all polls agree — but it remains a major question mark for the election. If Trump’s support among voters of color ends up closer to the average, Harris will be in better shape.

The other factor is that young voters and voters of color — two groups that overlap a lot — make up a disproportionate share of the undecided. That follows the pattern of previous elections in which those groups have been late deciders.

Roughly 1 in 6 voters tell pollsters either that they haven’t made up their minds or could still change their minds by election day.

Only some of those voters truly waver between Trump and Harris. Whether to vote at all is the bigger question for many of them.

These uncertain voters generally do not have strong ideological convictions — they usually identify themselves as moderate.

Above all, they tend to not pay a lot of attention to political issues.

If you want a mental image, think of young parents scrambling to balance work with getting a toddler to day care.

They have a lot of bills to pay and are very sensitive to the cost of living. Housing costs, in particular, loom larger for them than for older voters, who are much more likely to own a home and not be looking to move.

They’re typically too pressed for time to follow the details of a candidate’s tax plan or the latest developments in the Gaza war. Instead, they tend to use rough impressions to make up their minds about a candidate — the sort of mental shortcuts that pollsters try to capture by asking which candidate “cares about people like me” or “can bring about the right kind of change.”

The debate may be a key opportunity for Harris to catch their attention.

Anti-Trump Republicans

There is one group of potential swing voters who have a very different profile — Republicans with doubts about Trump.

As the primaries showed, a substantial swath of Republicans didn’t want Trump to be their nominee. Most have made their peace with the outcome, but not all.

The Harris campaign has eagerly courted the holdouts, giving prime Democratic convention speaking slots to former Rep. Adam Kinzinger of Illinois and former Georgia Lt. Gov. Geoff Duncan.

That’s why attention this week focused on two conservative Republican former lawmakers who publicly declared they would not vote for Trump.

Former Sen. Pat Toomey of Pennsylvania made his statement Tuesday in an interview on CNBC.

“When you lose an election, and you try to overturn the results so that you can stay in power, you lose me, you lose me at that point,” he said, adding that he would not vote for either Trump or Vice President Kamala Harris.

“It is an acceptable position for me to say that neither of these candidates can be my choice for president.”

On Wednesday, former Rep. Liz Cheney, speaking at Duke University in North Carolina, went further:

“Donald Trump, no matter what your policy views are — no matter if you are a conservative Republican or not — Donald Trump cannot be trusted with power,” she said.

“I don’t believe that we have the luxury of writing in candidates’ names, particularly in swing states,” she said, differing with Toomey. “And, as a conservative, as someone who believes in and cares about the Constitution, I have thought deeply about this, and because of the danger that Donald Trump poses, not only am I not voting for Donald Trump, but I will be voting for Kamala Harris.”

Cheney plans to campaign actively over the next several weeks, making the anti-Trump case in swing states.

Only a small number of partisans will be willing to cross the line and vote for the other side’s candidate. But in an election poised on a knife’s edge, they could matter. Their effect is yet another hard-to-predict factor in what has turned out to be a highly unpredictable year.