So I've made my tentative predictions for the results tomorrow. Let's dig into the Senate a little bit more.
My basic assumption here is that Republicans are likely to hold all open GOP seats and are (barring something very strange) clear favorites to get at least 4 Democrat seats (AR, IN, ND, and WI).
And then the toss-ups. What follows below is my ranking of toss-ups, from what I guess to be most likely to switch to least likely. I emphasize that this order is very, very tentative, and I would in no way be surprised if some of the seats higher up the list stayed Democrat while lower seats switched parties.
The Good Chances
Pennsylvania
Pat Toomey has led throughout most of the polling cycle, even if Joe Sestak has closed the gap a little recently. Sestak has a reputation as a strong closer, but I don't think he's got the numbers. Sestak is a pretty far-left Democrat, who could have won in 2006 or even 2008 (maybe), but Pennsylvania doesn't seem like his territory in 2010.
Illinois
Mark Kirk has had a very slim lead over Alexi Giannoulias for months now. Giannoulias has been dogged by ethical questions throughout this campaign. Neither candidate has ever really cracked the high 40s in polling, so there could be a surprise here, but it looks like Kirk has the edge.
Nevada
Sharron Angle has struggled against Harry Reid. Neither candidate seems particularly popular in Nevada, but Angle seems to be pulling ahead in the final days of the campaign. With Tuesday approaching, Nevada voters don't seem comfortable with pulling the lever for an increasingly left-wing Reid and for the Obama agenda.
Colorado
Republican Ken Buck has had a few difficulties on the campaign trail, but Democrat Michael Bennet is facing a very hostile political environment. A divisive governor's race (with a failed GOP candidate and an empowered Tom Tancredo) may pull down Buck. But polling gives Buck an edge, and he seems to be pulling away from Bennet.
The Unknowns
West Virginia
This state is puzzling. It has a radical antipathy to Barack Obama and his agenda. And yet it may be on the verge of sending a Democrat into the Senate. Democratic Governor Joe Manchin is personally very popular and separated himself from the administration on cap-and-trade very early on. But now Manchin has much more explicitly distanced himself from the White House, including reversing some of his former positions. For example, in the heat of the health-care battle, Manchin supported Obamacare; now, in the heat of the campaign, he has denounced that measure. Republican John Raese had successfully attached Manchin to the Democratic agenda in the early fall, but now Manchin seems to have successfully danced away from his old allies and has regained his lead in the polls. I'm still somewhat bullish for Republicans in this race, though. Will WV voters really go into the voting booth on Tuesday and not fear that Manchin will, once in office, cast his vote for "progressive" plans? I think those reservations could sway some voters---Tuesday will tell if they sway enough.
Washington
Patty Murray is vulnerable, and Dino Rossi has run a good campaign. Coming up on Tuesday, this race is about as close as it can get. A wave could definitely propel Rossi over the top.
The Long Shots
Connecticut
It seemed in early October that Linda McMahon was narrowing the gap against Democrat Richard Blumenthal, but the rest of October saw Blumenthal expand his lead. A Republican win could happen, and there are a number of close House races, which could help McMahon.
California
This race seems within five points, but those are a long five points. Under perfect storm conditions, Carly Fiorina could pull off a win over Sen. Barbara Boxer.
Delaware
This state is so small that a surprise could happen. But make no mistake: it would be a SURPRISE. The RCP average of polls has shown little real movement in the race for almost six weeks, and the picture isn't a pretty one for Christine O'Donnell---a 10+-point Coons lead. O'Donnell did surprise some pundits with her victory over Mike Castle in the Republican primary, but polls taken prior to the race did show her leading Castle. That kind of evidence is lacking this time around. Maybe her 30-minute epic commercial airing today and tomorrow will help her beat Coons.