Washington has statistics. Americans have receipts. The midterms start now.

If you think you know who’s winning the midterms, I have some bad news.

The voters who will decide them are just starting to pay attention.

I say this as someone who loves polls. They tell us what people care about, what they’re worried about and where the political opportunities are.

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But summer horse-race numbers come with a giant asterisk:

The electorate isn’t finished yet.

We saw it all summer.

In Michigan, Abdul El-Sayed appeared headed toward a comfortable Democratic Senate primary victory. He won by about a point.

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In Wisconsin, Francesca Hong led David Crowley by roughly 20 points in two polls. Crowley won.

In Minnesota, a public poll had Angie Craig ahead of Peggy Flanagan by two. Flanagan won by nearly 20.

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The lesson isn’t that polls are wrong.

It’s that voters move.

And now comes the part of the campaign when they start moving.

Labor Day is the unofficial beginning of the election season for the people who don’t spend August obsessing over politics.

Which is to say: most people.

They don’t know who won the week. They didn’t see the viral clip. They aren’t refreshing the generic ballot. They have never described themselves as “low-propensity voters.”

They’re busy.

And politics has developed a very bad habit of confusing the people who are paying the most attention with the people who will ultimately decide the election.

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We confuse loud with large.

A few thousand furious people can generate an enormous amount of internet.

Millions of people wondering why their grocery bill is still so high can generate almost none.

Then Election Day comes along and counts them exactly the same.

This is why I’m less interested in who moved from 47 to 48 this week than in what sits underneath the number.

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Who is certain?

Who is movable?

Who is going to vote?

And which party is actually reaching people who weren’t already with them?

Because there is a huge difference between making your supporters more enthusiastic and turning more people into your supporters.

Attention feels like momentum. Persuasion creates it.

Which makes what Republicans are doing in Dallas this week fascinating.

For the first time, the GOP is holding a national convention built around a midterm election.

They wanted the stage.

They got it.

Now the question is whether they use it to talk to themselves or to the voters they still need.

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Because Republicans don’t have an awareness problem.

Everyone knows Donald Trump.

They don’t have an enthusiasm problem among their most loyal supporters.

They have an affordability problem.

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Americans don’t experience the economy through a press release.

They experience it at checkout.

Washington has statistics. Americans have receipts.

They know what groceries cost. They know what happened to their insurance premium. They know what the electric bill looks like. They know whether a decent salary suddenly doesn’t feel so decent anymore.

Republicans can spend their time in Dallas explaining why the economy is better.

Or they can answer the question voters are actually asking:

When does my life get more affordable?

That’s the opening.

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And Democrats see it too.

Texas Democrat James Talarico is counterprogramming the Republican convention with a statewide food drive focused on grocery prices and affordability.

It’s almost painfully perfect.

Republicans have the arena. Democrats want the grocery cart.

That’s the midterm fight.

Republicans can use Dallas to make people who already love Trump cheer louder.

Or they can give people who aren’t sold on Republicans a reason to reconsider.

One produces a great television moment.

The other produces votes.

And that’s what I’ll be watching in every poll from here to November.

Not simply who is ahead.

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Who is moving?

Who is persuadable?

Who is expanding their coalition?

Who is turning concern into choice and enthusiasm into turnout?

The political class spent the summer measuring attention.

Now we get to measure something much more important.

Persuasion.

The midterms start now.

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Republicans go first.

Get the popcorn.

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