For 12 years now, except for a brief period following a Senate defection in 2001, the Republicans controlled both the U.S. Senate and the House of Representatives. That could change on Nov. 7.

With the war in Iraq weighing heavily on voters' minds and President George W. Bush approaching the end of his term in two years' time, as well as some of the lowest approval ratings of any president in the modern era, Democratic lawmakers are hoping for some of their biggest gains in decades.

Up for grabs: All 435 congressional seats, 33 of the 100 Senate spots and 36 governorships, some of which will undoubtedly serve as future launching pads for presidential aspirants two or three elections down the road.

Arnold Schwarzenegger (Rich Pedroncelli/Associated Press)

Two of these gubernatorial races are interesting almost purely on their own: After a rocky start, celebrity Republican Gov. Arnold Schwarzenegger looks to be heading toward victory in California (having won over his Democratic legislature). So does crusading ex-attorney general Eliot Spitzer, a Democrat, in New York.

Apart from their profiles, the two are also big environmentalists and their states have recently agreed to allow the joint trading of pollution credits, and to try to push climate change onto the national agenda.

The big prize this time out is which party gets to control the House and, possibly, the Senate and therefore set much of the legislative and media agenda in the run-up to the presidential election in 2008.

But if the Democrats should happen to win both houses of Congress on Nov. 7, it will almost certainly be seen as a referendum on the war in Iraq in many quarters. And the debate over withdrawing troops as quickly as possible will likely grow in intensity.

What's at stake?

Historically, the Democrats have controlled Congress, particularly the House of Representatives, which they once dominated for a 40-year stretch.

But that changed dramatically in 1994 with a massive swing to the Republicans of 54 seats in the House and 10 in the Senate.

The impetus for this has often been seen as Republican Newt Gingrich's deft Contract with America, a political agenda that brought with it a rise in male and southern voters, particularly those associated with the religious right.

The other factor that can't be discounted here is that the Democrats had become scandal-ridden while in control for so long and the continuing stalemate between Congress and the executive branch in the White House had become an issue of national concern.

In any event, to "take back" control, the Democrats will need to win 15 congressional seats from the Republicans and six Senate ones, which is not as easy as it looks.

Redistricting, as it's called, has consolidated incumbents in their areas of strength and recent elections have tended to show relatively little movement.

In the sixth year of Bill Clinton's regime, for example, in 1998, there was virtually no Senate movement from the previous election two years earlier.

In the equivalent election in Ronald Reagan's tenure, 1986, there was a shift of six seats from the Republicans to the Democrats, which returned them control of the Senate for the next eight years.

If the Democrats are able to make a breakthrough, however, the prize is that they get to control key committees, particularly defence and security-related bodies.

They have been promising to use these platforms to delve more deeply into the administration's handling of the war in Iraq, the use of prewar intelligence and the contracts that have been given out for reconstruction.

Winning the governor's chair also means that party gets to control the voting rules and apparatus in that state for the presidential election in 2008.

In the last race in 2004, there were no more important swing states than Florida and Ohio and both are currently up for grabs. Jeb Bush, the president's brother, isn't running again in Florida because he has reached his term limit.

Many top Democrats have also been agitating for more federal funding for stem cell research and other socially liberal causes, which would both put Congress at odds with the White House and create possible new agenda issues for the next presidential campaign.

At the same time, Democrats have traditionally been the more isolationist of the two mainstream parties. So a Democrat-controlled Congress might not necessarily bode well for Canada when it comes to trade or border-crossing disputes.

Senate races to watch

In its assessment, the New York Times suggests there are as many as 11 close Senate races that bear watching on election night. The CBC's Washington correspondent, Henry Champ, narrows the field to eight and he also suggests the Democrats will have a tough time getting the six they need, even with the wind at their backs.

Harold Ford Jr. (Ron Edmonds/Associated Press)

Champ's list also includes Tennessee, an interesting race with a strong Democratic challenger in Harold Ford Jr. who is trying to become the first African-American to be elected to the Senate in the South.

That race is also turning into a symbolic test of whether the Democrats can establish a beachhead in the conservative heartland, the so-called Red (or Republican) states.

• See Champ's blog, Washington File

Some of the most endangered Republican incumbents appear to be Rick Santorum in Pennsylvania, Mike DeWine in Ohio (the scene of so much presidential drama in the 2004 elections) and septuagenarian Conrad Burns in Montana , who has been linked to a lobbying scandal.

Two other Republican incumbents in tough fights include George Allen in Virginia, who has seen his double-digit lead almost totally expire in recent weeks, and Lincoln Chafee in Rhode Island.

A moderate Republican, Chaffee has long been one of the more popular Senators on Capitol Hill. If he falls, it will likely be because his opponents have made him the proxy for Bush keeping control of the Senate.

With only a few weeks to go, there have been reports that Republican headquarters is pulling its TV ad budget from several races and using it to bombard Missouri and Tennessee (and possibly Virginia), building what amounts to a political firewall to keep the Democrats from gaining control of the Senate.

If fortunes shift or local issues take precedence, the Republicans' best chance of picking up a seat or two look to be Minnesota, where there is no incumbent, or possibly New Jersey, where incumbent Robert Menendez, a Democrat, has been hurt by corruption charges against the state Democratic party.

Joe Lieberman (Jim Bourg, Pool/Associated Press)

Another intriguing race will be Connecticut, where Senator Joe Lieberman, a former vice-presidential candidate, lost the Democratic primary to businessman Ned Lamont, who took a much stronger anti-war position.

Lieberman is running as an independent and appears to be leading in the polls. But this could easily turn into a legitimate three-way race and the outcome will surely be seen as a referendum on how quickly the U.S. should get out of Iraq.

Congressional races to watch

There are so many — all 435 up for re-election — that it's hard to pinpoint which ones stand out.

The Los Angeles Times suggests, however, that with the president's approval rate as low as it is in New England and the northeast in general (27 per cent), the Democrats could make up their 15 seats within that region alone.

That may be a bit of a stretch: There are strong, well-heeled Republican candidates in specific districts in New York and Connecticut who are trying hard to localize their fights.

But if you throw in Ohio, where Republican Bob Ney just pleaded guilty to corruption charges, and a handful of tight races in Pennsylvania and Indiana, then it's not impossible to see that entire northeast corner of the U.S. painted Democrat blue.

Other close House races look to be in Colorado and Florida. In Florida, the recent scandal that led to the resignation of Republican Mark Foley, for sending suggestive e-mails to teenage congressional pages, looks to have thrown a wrench into the long-standing Republican hegemony in that state.

A swing of 15 seats is not out of the question in congressional elections, though the House has been remarkably stable over most of the past dozen years. Prior to the 54-seat swing to the Republicans in 1994, there was a 17-member swing to the Democrats in 1990 and 1982; everything else has been all single-digit changes.

The governors

Given that a presidential election is only two years away (and campaigning starts in earnest next fall), those governors running for election this time are not likely to spring that quickly from the state house to the White House campaign trail.

Still, don't rule out the ambitious Spitzer, a crusading, headline-loving Democrat running in New York, down the road. And there are plenty of other interesting contests to be decided on Nov. 7 as well.

For one, Massachusetts will elect either its first black (Deval Patrick) or its first female governor (Kerry Healey). But the subtext here is that Healey's is a proxy vote for her former boss, ex-governor Milt Romney, who has been gearing up for the Republican presidential nomination in 2008.

Romney has turned this into a referendum on the "Romney-Healey achievements" and if Patrick, a popular U.S. attorney, wins, that won't help Romney show that he has a home base from which to launch a national campaign.

Some of the gubernatorial races are of interest largely for their celebrity factor: Aside from Schwarzenegger in California, these include Texas , where singing satirist Kinky Friedman has finally got himself on the ticket as a (long shot) independent, polling about 10 per cent of the vote; and Pennsylvania, where former all-star NFL receiver Lynn Swann is running as the Republican candidate.

Jennifer Granholm (Paul Sancya/Associated Press)

For Canadian content, it will be hard to overtake Michigan. Jennifer Granholm looked to be the new TV-ready star when she was first elected in 2002. Only the fact that she was born in Canada prevented her from being considered a presidential contender some day.

But a stagnant (auto industry) economy has put her on the defensive and she now finds herself in a tough fight with Republican Richard DeVos, son of the Amway founder, who is spending his own millions to blanket the airwaves.