Nation Review has an 9/27
article predicting a two seat gain in the Senate for the Republicans. The author, John Miller, puts the closest races into "Likely", "Leaning" or "Toss Up" categories. Miller, for the most part, stays with calls he made in July, regardless of what the polls are doing. When I rate the races with the latest information, I come up with a one-seat gain for the Democrats, giving them control of the Senate if Edwards is VP.
Here is the state of the Senate races, with both my assessment in bold:
Alaska - Leaning Democratic takeover
That last two polls that
RealClearPolitics.com has up gives the Democrat Knowles a 3 point and 6 point edge over the Republican incumbent Murkowski. I don't know if you can invoke the incumbent rule (less than 50% is death) for Murkowski because she was appointed to the position in 2002 (by her dad), but I would doubt that the majority of undecideds are going to vote for her. Miller rates it a "Toss Up".
California - Leaning Democratic retention
In a 9/24 to 10/3 poll, the Democrat incumbent Boxer is ahead 48% to 32%. That is an anemic lead for an incumbent, but Jones doesn't seem to be getting any traction. Miller now rates it a "Likely Democratic retention".
Colorado - Leaning Democratic takeover
That last three polls that RealClearPolitics.com has up gives the Democrat Salazar a 0 point, 2 point and 11 point edge over the Republican Coors, which averages to over 4%. Miller rates it a "Toss Up".
Florida - Toss Up
Kos has a post up on this race. The average of the last three independent polls is a tie. However, the Democrat Castor has a new ad out that refutes the Republican Martinez's main attack and turns it back on him. This is an ACT state, so I am expecting the Democrats to win the ground game. However, Jeb Bush is the Governor, so I am expecting election day shenanigans. Miller rates it a "Leaning Republican takeover".
Georgia - Likely Republican takeover
In a poll released on 10/8, the Republican Isakson is ahead of the Democrat Majette 49% to 33%. Miller rates it the same.
Illinois - Likely Democratic takeover
All Keyes is providing is laughs
Kentucky - Leaning Republican retention
This should have been a no-contest and Miller doesn't even mention. However, the Republican incumbent Bunning has been extremely odd lately, so much so that the Kentucky's largest newspaper has recently published an editorial asking him to hold a press conference to disprove questions about his mental health. Apparently, a recent Survey USA poll showed Bunning's lead down to 11, and that was before a series of inexplicable actions by Bunning around the only debate with the Democratic challenger Mongiardo. The DSCC recently gave Mongiardo some badly needed funds. If Bunning doesn't hold a press conference soon, look for the speculation to eat into his lead.
Louisiana - Toss Up
Louisiana is different than the rest of the US, with a all-contestants primary on Nov 2nd and a run off on Dec 4th. The three latest polls on RealClearPolitics.com has the Republican Vitter ahead of three different Democratic challengers with an average of 43%. The big question is how many supporters of Democratic candidates will Vitter gain in the run off? Louisiana is lean Bush, but elected a Democratic Senator in 2002. Miller rates it the same.
Missouri - Likely Republican retention
The Republican incumbent Bond is way ahead of the Democrat Farmer. Miller rates it the same.
North Carolina - Toss Up
The Democrat Bowles was an early leader, but Republican Burr has caught up.  The last four polls from RealClearPolitics.com have Bowles twice with a 1 point lead and Burr twice with a two point lead. Miller also rates it a "Toss Up".
Oklahoma - Toss Up
The last four polls from RealClearPolitics.com have the Republican Coburn ahead in 3 by 5, 1 and 2, but behind by 2 in a fourth. What strikes me about these polls is that the undecideds are averaging nearly 20%. The only idea that comes to mind that may explain this is perhaps Oklahoma's large Native American population feels uncomfortable telling strangers their political preference. Given Coburn's inflammatory comments towards Native Americans, their turn out will probably decide the race. Miller rates it a "Leaning Republican retention".
Pennsylvania - Leaning Republican retention
In an early October poll, the Republican incumbent Specter is ahead 46% to 32%, with 6% choosing third party candidate Clymer. This is an ACT state, Kerry has a sizeable lead here and Bush is pulling his ads in the state. A sign of how the Democrats think this is winnable, Max Cleland recently campaigned there for Hoeffel. I think if Hoeffel can get a little further down field, ACT can kick a field goal for him. Miller rates it a "Likely Republican Retention".
South Carolina - Leaning Republican takeover
The last two polls from RealClearPolitics.com have the Republican DeMint ahead of the Democrat Tenenbaum by 6 and by 3. SC is a heavily leaning Bush. Miller also rates it a "Leaning Republican takeover".
South Dakota - Toss Up
The only poll done in October has a tie between the Democratic incumbent Daschle and the Republican Thune. Given that Thune was South Dakota's lone Representative, the usual break for the challenger may not hold here. Miller rates it the "Leaning Democratic retention".
Washington - Likely Democratic retention
The Democratic incumbent Murray is crushing the Republican Nethercutt. Miller rates it the same.
Wisconsin - Likely Democratic retention
The last two polls from RealClearPolitics.com have the Democratic incumbent Feingold opening a comfortable lead over the Republican Michels. Miller rates it the same.
So, Miller has a likely Republican takeover in Georgia, leaning Republican takeovers in Florida and South Carolina, no leaning Democratic takeovers, a likely Democratic takeover in Illinois and four toss ups (Alaska, Colorado, Louisiana and North Carolina). Miller assumes that the toss ups will go two to the Democrats and two to the Republicans. Therefore, Miller is predicting a two seat gain in the Senate for the Republicans.
I have a likely Republican takeover in Georgia, a leaning Republican takeover in South Carolina, leaning Democratic takeovers in Alaska and Colorado, likely Democratic takeover in Illinois and five toss ups (Florida, Louisiana, North Carolina, Oklahoma, South Dakota). Four of the five toss ups are currently Democratic seats. My guess is that Florida will be a comfortable win for the Democrats and the Democrats will split the other four toss ups, giving them a one seat gain in the Senate. However, control of the Senate could easily come down to the results of the December Louisiana run-off.