FiveThirtyEight founder and election forecaster Nate Silver on Monday offered his final projections for the midterm elections, arguing that a number of factors are conspiring to make Republican chances of keeping the majority in the House "fairly slim."

Silver gave Democrats a roughly 86 percent chance of winning the majority in the House. The party must pick up at least 23 seats on Tuesday to retake the majority.

"Democrats need a couple of things to go wrong to lose tomorrow because not very much is going right for Republicans," Silver wrote.

ADVERTISEMENT

Silver said Republicans still stand a slim chance of retaining the House majority thanks to a strong economy and favorably drawn districts. The latter factor, Silver wrote, forces Democrats to win the popular vote by at least 5 percentage points to secure the majority.

Democrats, however, are aided by President Trump Donald John TrumpOmar fires back at Trump over rally remarks: 'This is my country' Pelosi: Trump hurrying to fill SCOTUS seat so he can repeal ObamaCare Trump mocks Biden appearance, mask use ahead of first debate MORE’s low approval ratings, strong fundraising numbers, a large number of Republican retirements and a historical precedent of the president’s party losing ground in the midterms, Silver noted.

"Democrats have been dealt a good hand and have done a great job of playing it, maximizing their number of opportunities to make seat gains," Silver wrote. "There’s still a chance — about a 15 percent chance — that their voters won’t turn out in the numbers they need, and they’ll fall a few seats short."

"But it would require polling and a lot of other data to be fairly wrong, and it would defy a lot of historical precedent as to what happens in midterm elections under unpopular presidents," he added.

Republicans have a more favorable path in the Senate, where the party stands a roughly 80 percent chance of retaining the majority, Silver projected. There are nine GOP senators up for reelection this year, compared to 26 Democrats, 10 of which are running in states Trump won in 2016.

Republicans currently hold a 51-49 edge in the Senate.