There are a few changes to report in the nation’s Senate races since we last reviewed them in July — almost all of them in favor of the Democratic candidates. Yet the fundamental outlook hasn’t changed terribly much.

The Democrats will pick up a fair number of seats to pad their slim 51-to-49 margin. They are defending a mere 12 seats, and all their incumbents are running again. The Republicans have drawn the short straw, trying to protect 23 seats with five incumbents retiring in a tough political environment for the GOP.

Democrats are on target to add a minimum of four seats. They may gain as many as seven or eight. Unlike some other prognosticators, however, we still believe the Democrats are unlikely to gain the nine seats required to hit the magic number of 60 needed to shut down filibusters.

Actually, Democrats need an additional 10 seats to get to 60. Does anyone really count Sen. Joseph Lieberman (I-Conn.) as a reliable party vote on much of anything, especially in national security matters and foreign policy?

As we noted in our earlier analyses, the Senate has changed party control six times: in 1980 (D to R), 1986 (R to D), 1994 (D to R), 2001 (R to D), 2002 (D to R) and 2006 (R to D). This is no longer a rare event. Still, 2008 is now certainly not going to generate a seventh shift.

It is the 10 hottest Senate elections that will determine the final tally in 2008. The states that are hotly contested are: Alaska, Colorado, Kentucky, Louisiana, Maine, New Hampshire, New Mexico, North Carolina, Minnesota, Mississippi, Oregon and Virginia.

The Old Dominion hasn’t moved nearly as far as New Hampshire across the political spectrum, but it has undeniably become more Democratic in recent years, primarily because of the growth of moderate Northern Virginia.

The GOP has lost races for governor in 2001 and 2005, U.S. senator in 2006, and the state Senate in 2007. The man who started the movement to the Democrats, former Gov. Mark Warner, is headed to the Senate in 2008. On May 31 Republicans nominated Warner’s controversial predecessor, former Gov. Jim Gilmore, who has little money or remaining appeal.

Gilmore’s already severe problems were compounded by what happened at the convention. He barely squeaked by a gadfly state legislator, Del. Bob Marshall, with a mere 50.3 percent of the votes cast.

The Virginia GOP has moved farther right at a time when the state as a whole has dramatically moderated, making the Republican Party’s brand unpalatable to key swing centrists and independents who fund the candidates. All this is great news for the Democrats. Mark Warner will succeed the retiring Sen. John Warner (R) in a landslide for the Democrats.

Democrats will control the governorship and both Senate seats for the first time since January 1970. Virginia’s years as a Republican stronghold are well over. Democrats hope that Warner’s likely 60 percent-plus showing will provide the votes needed for Barack Obama to become the first Democrat to carry Virginia in a presidential election since LBJ in 1964.

Therefore, the early outlook is for another very good year for the Democrats. The Crystal Ball has Democrats in line for pick-ups in Virginia, New Mexico, Colorado and Alaska, in that order of likelihood. Oregon, Kentucky and North Carolina comprise the second tier of possible Democratic gains, with Oregon and North Carolina’s GOP incumbents already involved in toss-up races. The third-tier states, Maine and Minnesota, are both quite a stretch for Democrats, though not impossible, with Minnesota more likely than Maine to fall from GOP hands.

In sum, the Democrats are on track to win somewhere between four and eight additional Senate seats. While we will predict every contest by Nov. 4 — and call all toss-ups definitively — our estimate in early October is that Democrats most probably will capture a total of six seats, bringing them to 57 of 100 (counting Joe Lieberman at the moment.)

That is a more than respectable haul for one election night — but it is a few seats from the 60 reliable votes needed to tame the chaotic Senate.