Back in 2007, as an energy saving measure, the United States extended the date on which daylight saving ends, from the last Sunday in October to the first Sunday in November. That means that US elections — held on the Tuesday after the first Monday in November — will now sometimes happen under daylight saving, and this is one of those years: so today the east coast states, for example, instead of being eight hours ahead of eastern Australia, are still nine hours ahead (or, for pedants, 15 hours behind, since it’s still Tuesday there).

That makes life a bit easier for election-watchers here. Results from today’s mid-term elections started coming in shortly after 9am, Melbourne time, and the polls on the west coast close five hours after that, so the picture should be pretty complete by mid-afternoon. But of course there are bound to be a few close races that can’t be called until tomorrow or later, and it’s always possible that control of one or the other house could hang on one of them — as the Democrats’ senate takeover did in 2006.

But before looking at what’s become known so far, let’s recap what we’re looking for.

The Democrats, after two good election cycles, currently control the presidency, both houses of Congress, and a majority of governors and state legislatures. The presidency isn’t up for election again until 2012, but pretty much everything else is being voted on today.

In 2008 the Democrats won a 79-seat majority in the house of representatives, on a two-party vote of 54.6%. The whole house is up for re-election today, and the Republicans are strongly favored to overturn that majority and win control by a narrower but still comfortable margin. Nate Silver has a comprehensive hour-by-hour and seat-by-seat guide to how things might pan out.

Only a third of the Senate is elected every two years, which makes the Republicans’ task harder; six years ago was a good Republican year, so there are not as many Democrat-held seats on offer as there will be in 2012 and 2014. Even so, there is no doubt the GOP will make gains: North Dakota, Indiana and Arkansas are considered certain to fall, taking the current 59-41 Democrat majority to a best-case 56-44. A further nine seats are at some risk — roughly in order, Pennsylvania, Wisconsin, Nevada, Colorado, Illinois, West Virginia, Washington, California and Delaware.

Seven gains among those states would give the Republicans a majority; most observers regard that as out of reach, but they could get to 47 and might possibly make 49. Given that even a 59-41 majority has not always allowed Barack Obama to get his legislation approved (60 votes are needed to break a filibuster), 51-49 would clearly be a recipe for congressional gridlock.

Then there are the governors and state legislatures. Democrats currenly hold 26 state governorships to the Republicans’ 23, and also have the preponderance in state legislatures. There’s no doubt they will go backwards there as well: RealClearPolitics, for example, projects the Republicans to emerge with anywhere between 27 and 38 governors. And this is more important than in recent swing elections because 2010 is a census year, so the state legislatures in the coming term will have the responsibility of redrawing congressional boundaries — usually a partisan exercise.

So, what’s been happening so far? Silver has been liveblogging the results, and nothing so far has led him to change his overall expectations — he recently described it as “a fairly good night for the pollsters”. Eight house seats have been called as Republican gains (as of 9.20pm New York time), none of them being obvious surprises. The result will be in doubt for some time yet.

The Senate, on the other hand, is looking better for the Democrats than they might have feared. Indiana so far is their only definite loss (although North Dakota and Arkansas will certainly follow); West Virginia, thought to be at risk, has been called in their favor, and they are holding onto double-digit leads in Pennsylvania and Wisconsin (and, on very early numbers, in Colorado). Barring major upsets, the possibility a Republican majority has pretty much evaporated.

This is not going to be a good night for the Democrats, but it’s also not going to be a wipeout on the scale of 1994. Either way, as 1994 showed, it doesn’t tell us very much about Obama’s prospects in 2012: that will depend much more on what the economy does and how Republicans handle their increased power (including, of course, who they nominate against him) than on his legislative position.

Republicans are celebrating for now, but they have a fair way to go to recapture the trust that they forfeited during the Bush years.