21:39 GMT: A witty (and vulgar) website - "What the f___ has Obama done so far?" - is going viral on Facebook, with more than 53,000 fans. It presents a long list of various achievements in Obama's two years in office, and seems aimed at refuting Republican arguments that Obama has failed to bring his promised "hope and change".
21:21 GMT: BBC World News interviewed Democratic political consultant Peter Fenn just now. Fenn said that he expects Obama will act pragmatically and extend an "olive branch" to Republicans after the election and noted that Obama's approval rating is higher now than Clinton's in 1994, when Republicans won a huge midterm victory. Clinton was re-elected in 1996.
21:08 GMT: CNN's international channel is airing reports about the US midterms from its correspondents in Pakistan, China and Israel/Palestine. Kevin Flower says an Israeli official told him that a Republican-controlled Congress might be friendlier to Israel, but that he did not expect major changes from the administration in any case. Reza Sayeh says that if the GOP sweeps into power in the House and Senate, they might extract more conditions from Pakistan in exchange for existing US aid that amounts to billions of dollars.
20:29 GMT: Marc Lynch writes at Foreign Policy that he thinks a big Republican victory tonight will spell major changes for the United States' activities in the Middle East:
If the GOP takes Congress, it might overwhelmingly approve an Iran sanctions bill which ties the hands of the Obama administration and undermines its efforts to construct an effective negotiation strategy.   Or it might irresponsibly fail to confirm Ambassadors to Syria and Turkey, two key players in the region, for no good reason ... A GOP victory might embolden Israeli Prime Minister Netanyahu to continue to stonewall Obama and to stoke partisan opposition to his policies, for instance. Iran may conclude that it's pointless to do a deal with Obama if they think he can't deliver on his end.
20:12 GMT: No election is complete without allegations of voter fraud, and we have some of our first reports now from Kentucky, where by 2:30 pm local time the state's election fraud hotline had received 105 calls from at least 46 counties, including four allegations of vote buying, according to the Lexington Herald-Leader newspaper.
19:24 GMT: A spot of interesting news for the media geeks out there: For the midterms this year, the Washington Post newspaper has paid Twitter to promote its coverage on the "#election" search term. This means that anytime you search for "#election" on Twitter or click on the search term in the "Trending Topics" section, the Post's tweets will be given prominence by Twitter - they'll sit higher up in Twitter's vertical scrolling screen. It's the first time a media organisation has paid for a "promoted product" from the San Francisco-based Web 2.0 company.
It's still unclear how much the promotion has cost the Post.
19:16 GMT: You don't often see credible write-in campaigns in national US politics, but one in Alaska this year might actually work against the Republican tide. Incumbent senator Lisa Murkowski lost the Republican primary to tea party candidate Joe Miller (whose active-duty military guards infamously handcuffed a local journalist), but Murkowski didn't give up. Instead, she mounted a write-in campaign as a third candidate, and a poll released a couple days ago shows Murkowski, Miller and Democratic mayor Scott McAdams all hovering around 25 per cent of the likely vote.
19:02 GMT: To remind our readers, this year's midterm election involves all 435 seats in the United States' House of Representatives, 37 of 100 seats in the Senate, and 37 of 50 state governors' houses. Most observers are expecting Republicans to take the House back from Democrats the Senate will probably stay with the Democrats, but that's not a sure bet, and Republicans will probably steal some seats. Nate Silver, who became well known for his FiveThirtyEight polling blog (now rolled into the New York Times' coverage), has predicted that Democrats will lose 10 Senate seats to Republicans.
18:32 GMT: One of the most dramatic indicators of a pending Republican rout is a Gallup poll, conducted October 28-31, showing a 15 percentage point advantage for the GOP. Of the roughly 1,500 likely voters surveyed by Gallup, 55 per cent said they favored Republicans, while 40 per cent favored Democrats. Thanks to Al Jazeera's John Terrett, reporting from Washington DC, for highlighting the poll in his coverage.
18:22 GMT: We'll be updating our special midterm coverage page today and as the results unfold - a process that could take days or even weeks, if there are recounts - so make sure to watch there for all of Al Jazeera's election content. We'll also be providing live poll results via Google, which you can see here.
18:02 GMT: Welcome to the Al Jazeera English liveblog for the United States' 2010 midterm elections. This is the first national election president Barack Obama has faced in his 23 months in office, and polls show an electorate ready to deliver his Democratic party a stunning defeat. A Gallup survey of likely voters found that 55 per cent said they were going to vote Republican, compared to 40 per cent who said they would support Democrats. That disparity is unprecedented, according to Gallup.
We'll be keeping you up to date and informed throughout the day and night, linking to other coverage, aggregating thoughts from social media, and providing expert analysis from our own correspondents and analysts. Al Jazeera's television coverage of the election begins at 7 pm Eastern time, or 23:00 GMT.