OF THE 100 seats in the Senate, 35 are up for re-election this year. The Senate is split 51-49 in favour of the Democrats and, if they can push their numbers up to 60, they will be assured a clear filibuster-proof majority.
Of the 10 seats seen as most vulnerable to switching party allegiance, all are Republican and some fairly prestigious names are likely to be sweating.
Alaska's Ted Stevens (Republican), a six-term senator, long known as a formidable fixer, has never been elected with less than 66 per cent of the vote. However he has just been convicted on seven felony counts over gifts/contributions from business. His trial testimony has been riveting and his seat is now marginal.
Senate Republican colleagues John McCain and fellow Alaskan Sarah Palin have called on him to stand down.
Senate minority leader Kentucky's Mitch McConnell (Rep), running for his fifth term, has a substantial fundraising advantage but his association with the Bush administration has also made his seat marginal and vulnerable to a local businessman.
In New Hampshire, John Sununu (Rep) faces a strong challenge from former governor Jeanne Shaheen who is leading in the polls. Also highly marginal in North Carolina, in her first bid for re-election, is Elizabeth Dole (Rep) who served in the Reagan and George HW Bush presidential administrations and is a former chairwoman of the Republican national senatorial committee. Her state has sent a Republican to the Senate for the last 35 years.
In Virginia, a lively contest between two former governors is being led by Democrat Mark Warner for the seat of retiring five-termer John Warner (no relation).
In Minnesota, Al Franken, the former Saturday Night Live satirical writer and actor, could pull off one of the surprises of the election by unseating Republican Norm Coleman.
The seat was formerly held by widely respected radical Paul Wellstone and the iconoclast Franken could well embarrass his own party's leadership by taking the seat.
Eleven governorships are also up for election with three involving non-incumbent contests. Of these, two may change hands - North Carolina's Democratic majority is marginal, while in Missouri, the party appears likely to gain control. In Washington, state, the Democratic governor is under threat.