As we near Election Day there are really 8 competitive elections out of 36. This is normal compared with previous years. If we assume that the other 28 elections are now done, the Republicans are going to go into Election Night with 47 seats and the Democrats with 45 seats. If you want to expand he realm of possibility to anything that is not 0% and 100% (assuming the Republicans have not already taken Arkansas and Kentucky), then there are 10 seats in play and the chamber is 45 to 45.
The Democrats are heavily favored in two elections: New Hampshire and North Carolina; the Republicans are heavily favored in Louisiana and Colorado. Colorado is the most interesting of these four states, as their new voting scheme could mess up the polling. Early voting does look ok for Democrats in Colorado, but it needs to be great.
The remaining states: Kansas, Georgia, Iowa, and Alaska, are all very tight. Kansas has a wildcard situation in both, leading candidate, by the slimmest of margins, is an independent. Further, the incumbent Republican governor is losing. So, people may vote differently than the polls if they panic about giving the Democrats too big of victory or where Orman, the independent will caucus. Georgia is also tough for the Democrats, because Nunn does not have enough to win without a runoff and a runoff lowers her likelihood of victory. Iowa is the only one of the four where the uncertainty is still a lot about the campaign, not Election Day. The Republican is a bit of wild card and has been stumbling down the stretch, avoiding spontaneous appearance sand interviews, trying “run out the clock.” Somehow Begich, the incumbent Democratic senator in Alaska, keeps the race close and everything comes down to whether he truly make a huge turnout on Election Day that overcomes challenger Sullivan’s slight lead in the polls.
Here is New York Times and FiveThirtyEight compared with PredictWise. FiveThirtyEight is surprisingly bullish on the Democrats in Kentucky.