Midterm polling: Democrats hold House lead, but Senate outcome remains unclear

Democratic candidates hold a consistent lead in the final wave of polls for the U.S. House of Representatives, with their advantage on the generic congressional ballot standing at eight points. All 50 most recent polls show Democrats ahead, a trend that accelerated in September as voter attention turned to the midterms. This level of support mirrors the 2018 cycle, when Democrats captured 41 House seats. The party's standing is bolstered by President Donald Trump's low approval rating, which CNN placed at 32 percent, a figure seven points lower than his rating entering the 2018 midterms.

The outlook for the Senate is less defined. Democrats need to net four seats to secure control. Currently, they are statistically tied or leading in eight Republican-held states: South Carolina, Alaska, Maine, Kansas, Texas, Iowa, Ohio, and North Carolina. They also lead in Michigan, where a Democrat is retiring. However, except for North Carolina, all these races fall within the margin of error. Cook Political Report rates Democrats as favorites in 220 House seats, which is two more than a majority, and projects a flip of between 12 and 22 seats.

Republican strategists argue their base turnout may outpace polling data. Nate Silver notes that in the last three presidential elections, final poll averages underestimated Republican support by an average of 3.8 points. Such a shift would be enough to flip the seven close Senate races back to the GOP. However, historical midterm data presents a different picture. Since 2016, midterm polls have slightly overstated Republican support by an average of 0.2 percent. Patrick Ruffini, a Republican pollster, points out that from 2018 to 2024, polls at this stage overestimated Democrats by 6.2 points in specific states including Iowa, Michigan, and Ohio.

Undecided voters in red states represent a final variable. CNN polling indicates that in Texas and Kansas, at least 60 percent of undecided voters are Republicans or lean Republican. This demographic offers potential room for the GOP to gain ground. Conversely, early voting numbers provide a clearer snapshot of current intent. As of Thursday, more than 42 million early ballots had been cast, a pace similar to 2012 and higher than the 39 million recorded in all of 2018. Democrats account for 44 percent of these ballots, compared to 31 percent for Republicans and 25 percent for Independents.

Partisan breakdowns in battleground states show Democrats outpacing Republicans in Maine by a ratio of nearly two to one, and leading by 15 points in Iowa. In Kansas, the gap is narrower, with Democrats at 45 percent and Republicans at 41 percent. Michigan presents a specific challenge for Democrat El-Sayed, who relies on young voters. Those under 40 make up only 14 percent of the early vote, roughly half of what polls estimate. Republican challenger Mike Rogers holds a 55 percent to 43 percent lead among voters over 45. If young voter turnout remains low, Rogers' chances improve beyond what current polls suggest.

The election is scheduled for Tuesday. Republicans retain a financial advantage and the ability to mobilize their base despite national polling headwinds. Democrats are positioned to take the House and hold between a 50 percent and two-thirds chance of securing the Senate.