The Greens’ lower house challenge in Victoria may have fizzled, at least compared to the campaign triumphalism, but its implications for future federal elections are intriguing.

Unlike the Democrats, the Greens do have a more geographically concentrated support base, which makes the chance of winning lower house seats a possibility.

And realistically, the Greens can only take lower house seats off Labor – because essentially they’re playing to a similar constituency which is also part of Labor’s electoral coalition – inner city progressives.

As the old working class nature of inner city seats has largely been wiped away by both social change and gentrification, that constituency is also more important to Labor majorities.

In Queensland, Labor strategists are worried by two factors potentially affecting the ALP vote in inner city seats federally. The first is the rise of the Greens – Peter Beattie’s state seat of Brisbane Central has seen the Green vote rise from 6.9% to 12.3% to 19.1% across the three successive elections from 2001.

The second is the erosion of the Labor vote at federal (if not state level) as apartment development and rising property prices bring young professionals into Labor seats who are swinging voters and whose vote is often closely tied to economic conditions. The yuppie mortgage belt, if you like. Some traditional Labor booths in New Farm and Kangaroo Point in inner Brisbane are now Liberal at federal level.

Outside Melbourne and Sydney, inner city federal seats tend to take in much more ground that’s essentially suburban in character. So at federal level, the Green vote is more likely to be around 10% than the 20% seen in the smaller and more exclusively urban state seats.

The danger for Labor is that while the Greens could not win seats like Brisbane or Adelaide, their increasing vote erodes Labor primaries in seats where the demographics push the Liberal primary higher.

In practice, the preference brouhahas in this year’s state elections have made little difference to elections where Labor has been returned with big margins. But in a close federal election, the Greens have an important strategic decision to make about inner city Labor seats and preferences. Because open tickets have the potential to deliver these seats to the Liberals, and thus perhaps the election, if the worst case scenario eventuates for Labor.

The Greens may have to decide which side they’re on.