What midterm election night polls told us — and what they can’t predict

Early data paints a dire picture for Democrats in the House, while control of the Senate is likely to be decided by three races

It now looks like the Republican party has a 59% chance of winning control over the Senate, according to the final FiveThirtyEight aggregate polling, which is weighted for pollster accuracy. Currently, the Senate is evenly divided, and Vice President Kamala Harris’s tie-breaking vote gives the Democrats control. And up until recently, it seemed like the upper chamber of Congress would stay in the hands of the Democrats. In fact, in late September, FiveThirtyEight gave the GOP only a 29% chance of gaining control with at least 51 seats. Clearly, a lot has changed since then.

On the House side, Republicans have a much higher projected 84% chance of gaining control. This is a significant increase from September, when that number was as low as 68% — but of course, that was still a pretty healthy number for Republicans. Most pundits and politicians alike presumed the House would be taken by the Republicans in the midterms. The Democrats currently have a five-seat edge in the 435-seat chamber.

Of course, these latest polls might still not be entirely accurate. The prevalence of partisan polling and the difficulties in sampling voters muddy the waters. There is a big gap between partisan polling versus non-partisan that tends to favor the GOP. But non-response bias — the idea that Republican voters are less likely to participate in polls — means their voters can end up being undersampled in polling, too.

There is no consensus on the number of younger voters, who could determine the outcome of the election either by voting (a big win for Democrats) or staying on the sidelines (to the delight of Republicans).

Early precinct data paints a dire picture for Democrats, according to Dave Wasserman, the House editor of the Cook Political Report newsletter. Looking at key House races in purple Virginia and red Florida, Wasserman tweeted that in key swing districts, as of noon, GOP turnout was badly outpacing Democratic turnout relative to last year (when Virginia had a governor’s race) and in 2020.

But he wrote: “In recent years, [Republican] voters have generally enjoyed their largest turnout advantage in the first 2-3 hours of [Election Day] voting. So, it’s possible these gaps will narrow – and these are just two states. But, these are just large differentials for Dems to overcome in the next few hours.”

Cook’s final projection for the House was 212 seats for the Republicans, 187 for the Democrats, and 36 tossups. Two hundred and eighteen are needed for a majority. It’s “an unusually uneven landscape, with a 15-30 seat GOP gain the likeliest outcome but a wide range of possibilities,” Wasserman said.

Control of the Senate is likely to be decided by three races, in Pennsylvania (currently held by the Republicans), and in Georgia and Nevada (currently held by Democrats).

In Georgia, FiveThirtyEight gives Republican Herschel Walker a 63% chance to unseat Democratic incumbent Raphael Warnock. However, this race may not be decided until a runoff election in December, given that it’s possible neither candidate gets at least 50% of the vote.

In Nevada, FiveThirtyEight gives Adam Paul Laxalt a 51% chance to flip the seat over Democratic incumbent Catherine Cortez Masto.

Nevada election expert Jon Ralston tweeted on Tuesday night: “In 2018, Election Day turnout in Clark County was 223K, and there were a quarter of a million fewer active voters. Overall turnout was 60% in Clark. Today’s is well under 100K, and overall Clark turnout is 40%. 40%! So there is either a big mail boost coming or a deep red wave.”

The biggest forecasting change is in Pennsylvania, an open seat currently in Republican control. In September, FiveThirtyEight gave television doctor and Republican candidate Mehmet Oz a 17% chance to win. In the final update tonight, it’s up to 57%.

Note that there is a lawsuit pending in Pennsylvania, in which Democrat John Fetterman is asking that undated mail-in ballots get counted. Last week, the state’s Supreme Court ruled that ballots sent in without the required date on an outer envelope would not be counted. Democrats are far more likely to vote by mail than Republicans, so it’s clear why Fetterman is rattled by the idea of these votes being thrown out. A lot may depend on whether or not he wins his lawsuit.

The lawsuit alleges that failing to count votes on what they say is a technicality “violates the Civil Rights Act and the First and Fourteenth Amendments to the US Constitution.” If Fetterman and Oz remain neck-and-neck, this issue — and thus this election — could end up being decided by the US Supreme Court. Unfortunately for Fetterman, the conservative-leaning SCOTUS has repeatedly decided against Democratic interests in voting rights cases, meaning that perhaps he shouldn’t hold out too much hope.