Yesterday’s Newspoll showed Labor’s support returning to its level of a month ago, suggesting that the previous poll — the one showing a 13.8% swing — was something of an outlier.

So if the two-party-preferred vote is currently stable in the region of 57%-43% –about a 10% swing, which would deliver a huge majority in the lower house — this is a good time to look at what that means for Kevin Rudd’s prospects in our other house, the Senate.

The Coalition won control of the Senate at the 2004 election, and now holds 39 seats (34 Liberals, 4 Nationals, 1 CLP), as against 28 Labor, 4 Greens, 4 Democrats and 1 Family First. With 36 senators (6 per state) not up for re-election, here’s a quick rundown of how the others might pan out:

New South Wales: In 2004, the combined parties of the right had 51.0%, against 47.6% for the left, so it split 3 Coalition and 3 ALP. A 10% swing would put the left on 57.6%, just over four quotas; provided the preferences all held, the third Coalition candidate would miss out and either Labor or the Greens would pick up the extra seat.

Victoria: Split almost evenly in 2004, 49.9% right to 48.9% left, but Family First got the last place because Labor and Democrat preferences were directed to them ahead of the Greens. Assuming that doesn’t happen again, a 10% swing would deliver a comfortable 3 Labor, 1 Green and 2 Liberals.

Queensland: The Coalition’s best state, elected 4 Coalition senators in 2004 on a 58.4%/41.1% right/left split. A 10% swing would just bring that back to roughly even, so 3 Coalition and 3 Labor.

Western Australia: In 2004 the right was just under 4 quotas, with 55.9% to the left’s 43.6%. That elected 3 Liberals, 2 ALP and a Green; with a 10% swing, the only likely change would be that Labor would win the third “left” seat instead of the Greens.

South Australia: Another 3-3 Coalition/Labor split in 2004, on a right/left vote of 53.4% to 46.0%. That means a 10% swing would still leave the left just short of a fourth quota, so if there were no surprises on preferences it would stay 3-all.

Tasmania: The left’s best state in 2004, just outvoting the right 49.8% to 49.3%, although the practice of directing preferences away from the Greens almost gave another seat to Family First. A 10% swing would bring in a third Labor senator, against 2 Liberals and a Green.

Territories: The Northern Territory is one-all whatever happens, but a 10% swing in the ACT would deprive the Liberals of a seat, probably giving it to the Greens instead.

Totals in the new Senate would be Labor 34 or 35, Greens 5 or 6, Coalition 35 and Family First 1.

The Coalition’s majority would be gone, but even with a barely believable swing, Labor would be well short of a majority in its own right.