Transcript for FiveThirtyEight updates Senate forecast

Yeah. The classic version size 38 cent for currently gives Republicans about two and three were about 60%. Chance of winning a majority. It gives Democrats about a one in reaching its. According to the fort. The most likely outcome. Is an even 5050 split. With the GOP maintaining control of the chamber because vice president Mike Pence. Caps the tie breaking vote but a wide range of outcomes is still possible. Anything from a democratic gain three seats to a Republican gain three seats wouldn't be all that surprising. Much has been sad about the difficult midterm senate Democrats. And this breakdown here legally shows you. Of the 100 senate's only 35. Election in two. Of the 65 not opt for forty to a Republican held. Vs just 23. Giving the GOP and the parents are Democrats need at least 2835. Seats on the ballot here. According to our forecast now there are 25 seats reviewed dams have higher than 60% chance of winning. Even if they managed to Wii and all of this 25 seats in order to win the set he would still need to win in three more seats. Either in races that we consider toss ups or lean Republican. This is why the GOP are two thirds favorites to win. Although nine possible. It's clear to see that tough road ahead for. Visit 530 dot com slash center forecast to explore the mob figures and.

This transcript has been automatically generated and may not be 100% accurate.