Midterm election forecasting by The Economist is predicting a 74 percent chance Republicans re-capture control of the U.S. House of Representatives and a 78 percent chance Democrats retain a majority in the Senate.
The estimates are based on its statistical forecasting model for American congressional elections, which has been run every election cycle since 1942.
This year, 469 congressional seats are up for election.
Midterm elections are usually a referendum on the current president and their party. In 36 out of the 40 midterm elections that have taken place in the U.S. since 1862, the president’s party has lost seats.
As of Sept. 7, The Economist’s midterm model predicts this trend will hold, with Republicans winning 224 seats in the House — six more than needed for a majority — and Democrats retaining control of the Senate, with between 47 and 55 seats.
The forecasting model runs 10,000 simulated elections each day, considering polling, demographics, fundraising, and historical results. Midterm election projections reflect the outcomes of these daily simulated elections.
Some pollsters and analysts have warned that in recent months, the chances of the GOP’s success in the midterms have been blunted, as the political landscape shifted for Democrats.
“Ever since the Supreme Court issued an unpopular ruling in June allowing states to ban abortion, the political environment has improved for Democrats,” said Dan Rosenheck, data editor and lead designer of The Economist’s forecasting model.
Prior to the U.S. Supreme Court’s decision in Dobbs v. Jackson Women’s Health Organization — which sent the issue of abortion back to the states — Republicans were expected to pickup two seats in the Senate and re-capture control of the House.
However, since that decision, along with gas prices dropping and Democrats passing a substantive spending bill, Democrats are slightly favored to win control of the Senate. The Economist also cites key Senate races where the GOP has nominated “potentially unelectable fringe candidates” as a factor that could help Democrats retain control.
“Mr. Biden’s net approval rating has risen by nine percentage points, and his party’s margin in ‘generic-ballot’ polls, which ask respondents which party they want to control Congress, has improved by three points,” Rosenheck said.
He added that skeptics may note that such polls over-estimated Democrats’ popular vote margin in 2020 House races, but that his forecasting model incorporates “predicted results based on ‘fundamental’ factors like a state’s electoral record, whether an incumbent is running, and, most importantly, in-state fundraising performance.”
The Economist’s analysis of its forecasting model states that Republican Senate candidates “have time to catch up,” noting that if Democrats’ prospects in Ohio, Florida, North Carolina or Wisconsin fade, so will their chances of retaining a Senate majority.
