The political pundits today are telling us that the next by-election will be in Alexander Downer’s blue ribbon Liberal seat of Mayo in South Australia.

Let me vary that with a forecast. I predict the next electoral event will be simultaneous by-elections in Mayo and the Victorian ultra-marginal Liberal seat of McEwen.

Back on 24 November 2007 the result in McEwen, in the two-party preferred vote, was 48,265 for Fran Bailey (Liberal) and 48,253 for Rob Mitchell (Labor) , a majority of only 12 votes. Labor appealed the result.

It is likely that the court of disputed returns will hand down its decision this week. Broadly speaking there are three possible outcomes which I list in order of probability.

The most likely is a by-election.

The second most likely is that the court will simply take the seat away from Bailey and give it to Mitchell. That would raise Labor’s number of seats in the House of Representatives from 83 to 84, with immediate effect. It would, of course, also lower the Liberal Party’s numbers from 55 to 54.

The least likely outcome is that Bailey would be confirmed in the seat.

In the event of the most likely outcome then Labor would have played its cards very badly. Having brought on the by-election (expecting to win) it would find itself compelled to fight that by-election which, given the trends of Gippsland, it would lose.

In the event of the second-most-likely outcome then Victorian Labor would feel triumphant. In the very week of its predictable drubbing in Gippsland it would suddenly find itself with an extra Victorian seat.

Technically the Mayo and McEwen by-elections would be different because the McEwen electoral roll would be confined to that of the November 2007 general election roll. But it is the political difference that is important. Whereas Labor can avoid a bad result in Mayo (simply by not contesting the seat) in practice it cannot avoid a bad result in McEwen.

The big winner in McEwen would be Brendan Nelson. By contrast the big winner in Gippsland was Warren Truss.