Democrats have about a 70% chance of winning the House, Nate Silver's FiveThirtyEight forecasts

  • Analytics site FiveThirtyEight's models give Democrats about a 70 percent chance of winning a House majority in November.
  • The outlet projects an average gain of at least 32 seats for the party, well above the 23 GOP-held seats needed to win control of the chamber.
  • FiveThirtyEight still gives the GOP about a 30 percent chance to keep control of the House, and much can change before the Nov. 6 elections.
House Minority Leader Nancy Pelosi (D-CA) 
Chip Somodevilla | Getty Images
House Minority Leader Nancy Pelosi (D-CA) 

Democrats have reason for optimism heading into November's midterms, according to one widely followed election forecaster.

The party has about a 70 percent chance of flipping enough Republican-held House seats to take a majority in the chamber, according to models from FiveThirtyEight, the analytics site run by data guru Nate Silver. The outlet's forecasts project an average Democratic gain of at least 32 seats, comfortably above the 23 districts the party needs to gain to win a majority.

The figures reflect a feeling among most election analysts that Democrats are at least slight favorites to win back the House. The party not in the White House generally performs well in midterm years. Democrats have tried to leverage opposition to health care and tax policies pushed by President Donald Trump and congressional Republicans into electoral success.

Democrats have generally led Republicans in polls measuring which party voters prefer to hold a majority in Congress. An average of polls measured by Real Clear Politics puts the Democrats' lead on the generic ballot at 6.8 percent.

Still, FiveThirtyEight gives the GOP about a three in 10 chance of holding on to its House majority. Also, much can change to affect races during the nearly three months between now and the Nov. 6 elections — both at the national level and in individual districts.

Should Democrats take the House, they have more power to stifle Trump's policy priorities or pursue their own goals, such as changing the Republican tax plan passed last year. A Democratic House could also become more vocal about impeaching the president, or push for more investigations into the Trump administration.

The models use data such as polling, fundraising numbers, historical election results and race ratings from nonpartisan analysts in every congressional district. FiveThirtyEight has three different forecasts that use varying points of data, which give Democrats at least a 68.5 percent chance and as high as a 75 percent chance of taking the House.

The site also assigns probabilities for candidates winning all 435 individual House races.

While Democrats appear to be favorites to take the House, Silver makes one significant note in outlining the methodology for FiveThirtyEight's forecast.

"Our models are probabilistic in nature; we do a lot of thinking about these probabilities, and the goal is to develop probabilistic estimates that hold up well under real-world conditions," he writes. "For instance, Democrats' chances of winning the House are between 7 in 10 and 3 in 4 in the various versions of the model upon launch — right about what Hillary Clinton's chances were on election night two years ago! — so ignore those probabilities at your peril."

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