If the polls are exactly right, the balance of power in Congress could look dramatically different after Tuesday’s midterm elections.

But that is a big “if.”

The final RealClearPolling averages heading into Election Day show Democrats with a substantial advantage nationally, while Democratic candidates lead in more than enough Republican-held races to give Democrats a majority if those polling leads held

What the Polls Say About the Senate

The Senate math is particularly striking.

Republicans hold a 53-47 Senate majority, meaning Democrats need a net gain of four seats to take control, according to Inside Elections.

If the current RealClearPolling averages translated directly into election results, Democrats would pick up several Republican-held seats.

In North Carolina, Democrat Roy Cooper holds a large polling advantage over Republican Michael Whatley.

In Kansas, Democrat Adam Hamilton leads Republican Sen. Roger Marshall. RealClearPolling’s competitive Senate tracker, using its competitive-race polling average through Sunday, puts Hamilton’s advantage at 3.6 percentage points.

Democrat Sherrod Brown also leads Republican Sen. Jon Husted in the Ohio special Senate election, while Democrat Mary Peltola leads Republican Sen. Dan Sullivan in Alaska.

Democrat James Talarico holds an advantage over Republican Ken Paxton in Texas, while Democrat Janet Mills leads Republican Sen. Susan Collins in Maine, according to the latest RealClearPolling Senate numbers.

Those contests matter because Democrats do not need to win all of them to take the Senate.

Inside Elections’ final outlook, updated Oct. 29, projects Democrats gaining four to six Senate seats. A four-seat gain would be enough to produce a Democratic majority, while a six-seat gain would produce a 53-47 Democratic advantage if no Democratic-held seats changed parties.

Several of the contests, however, remain close enough that relatively small polling errors could change the result.

RealClearPolling’s averages have Democrats ahead by narrow margins in Maine, Texas, and Alaska, making those races particularly important tests of polling accuracy.

What About the House?

The House picture is less straightforward.

The RealClearPolling generic congressional ballot average has Democrats at 52.1% and Republicans at 43.1%, a 9-point Democratic advantage through Sunday.

Individual surveys included in the average vary considerably.

AtlasIntel has Democrats ahead by 15 percentage points, while Morning Consult shows an 8-point advantage and NBC News has Democrats ahead by 7. Other recent polls range from a 4-point Democratic advantage to double-digit leads.

But a 9-point national advantage cannot simply be converted into a specific number of House seats.

House control is determined through 435 individual district elections, and differences in district boundaries, geography, turnout, and candidate strength mean the national popular vote and the number of seats won do not move together perfectly.

Republicans currently hold a 220-215 House majority, meaning Democrats need a net gain of three seats for control.

Inside Elections projects Democrats gaining 20 to 30 House seats. If that range were exactly right, Democrats would finish with roughly 235 to 245 seats, leaving Republicans with about 190 to 200.

Another prominent election handicapper sees a somewhat different range.

The Cook Political Report said Friday that Democrats could flip 12 to 25 seats, potentially giving the party as many as 240 seats.

The national polling and major race handicappers point in the same general direction: substantial Democratic House gains.

But Haven’t the Polls Been Wrong Before?

The polls have been wrong before, and sometimes in politically consequential ways.

Confidence in election polling took a hit after the 2016 and 2020 presidential elections.

Pew Research Center noted that many polls underestimated Republican support in both elections, particularly support for Donald Trump.

The biggest problems were apparent in state polling.

Pew cited an analysis by the American Association for Public Opinion Research that found the 2020 election produced the largest polling error in 40 years for the national presidential popular vote and the largest in at least 20 years for state-level presidential, Senate, and gubernatorial races.

The polling industry’s performance has not been uniformly poor, however.

Polls Were Much More Accurate in 2022

Polling performed considerably better during the 2018 and 2022 midterms, according to Pew, and the 2022 cycle was particularly accurate compared with recent elections.

The American Association for Public Opinion Research’s review of the 2024 election also found that publicly released polls provided a largely accurate picture of a close presidential race.

That followed the much more difficult cycles of 2016 and 2020.

Even the 2016 polling failure is more complicated than its reputation suggests.

AAPOR’s post-election analysis of the 2016 polling found that national polls were considerably closer to the final popular vote than many state polls. Hillary Clinton did win the national popular vote, as national polling generally indicated, but relatively small polling errors in several decisive states contributed to expectations that did not match the Electoral College result and Donald Trump’s victory.

That history matters especially this year because several Senate races sit within only a few percentage points.

A 2-Point Lead Is Very Different From a 10-Point Lead

A candidate leading by 1 or 2 points in a polling average is not in the same position as a candidate leading by 10.

A modest polling error in Maine, Texas, Alaska, Kansas, or Ohio could change an individual race and, because control of the Senate depends on only a handful of contests, potentially change control of the chamber.

Polls are therefore best understood as snapshots of the electorate before votes are counted, not election results.

Tuesday’s results will provide the answer to the question hanging over all of those numbers: Did the polls get it right this time?

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