The battle for the seat of Melbourne at this year’s federal election will be nothing short of a bruising affair. Melbourne is of enormous symbolic importance to both Labor and the Green Party.

For Labor, the Melbourne contest is emblematic of its struggle to contain its increasingly fragmented base of support. Formerly a safe working class seat, Melbourne is now home to a growing number of affluent left-leaning voters. A failure to regain the seat will be widely interpreted as a sign that the party is losing the battle to find common ground between its progressive and more traditional working class constituencies.

In the case of the Greens, Melbourne will serve as a test of its success in converting more progressive inner metropolitan voters into rusted on loyalists. If the Greens cannot grow its support in an electorate with a demographic profile as sympathetic as Melbourne’s, then the party’s plans for political and electoral expansion beyond the Senate are sorely limited.

A loss in Melbourne will also prove problematic for the Greens in another important respect. In a party with seemingly more introverts than extroverts, Adam Bandt has emerged as one of the Greens most effective media performers. In the aftermath of Brown’s retirement particularly, Bandt’s accessible manner has helped to balance Christine Milne’s more abrasive style.

It is not surprising therefore that Bandt has been in permanent campaign mode in Melbourne since his election. But retaining the seat will be difficult, a point which Bandt acknowledges.

Bandt’s biggest obstacle takes the form of the two main parties.

While the big players have agreed about little over the course of the 43rd parliament, they do share a desire to expunge the Greens from the cross benches of the House of Representatives.

The big parties might be prepared to endure the indignities of minor parties in the Senate but they show little appetite for these interlopers in the House of Representatives, which is the equivalent of political holy ground for Australian parties.

The ALP will redouble its efforts to recapture Melbourne, which is likely to be assisted by its decision to establish its campaign HQ in Victoria.

The ALP has once again endorsed Cath Bowtell as its candidate for Melbourne. This time Bowtell’s campaign will not be hamstrung by lack of advanced notice, which blighted her efforts in 2010 owing to Tanner’s late resignation from the seat.

Bowtell is a good fit for Melbourne. Her liberal political views (not to mention her gender and local activist credentials) will bolster her appeal among the more progressive segments of the Melbourne electorate. Similarly, Bowtell’s union connections (she works for the ACTU) will enhance her credibility among Melbourne’s more traditional working class voters.

More importantly, Bowtell’s prospects of winning Melbourne are likely to receive a much needed boost from the Liberals.

While both of the main parties have been quick to denounce the Greens as radical, this belief resonates strongest within the Liberal Party and among its supporters.

It should come as no surprise that the Liberals are poised to preference the ALP ahead of the Greens in Melbourne.

There is very little risk for the Liberals in preferencing against the Greens. The Liberal’s anti-Green preference strategy was touted as a public relations triumph for the party at the Victorian State election in 2010.

There is no doubt that the wagons are circling Bandt. He is unlikely to win Melbourne on primary votes, even with aid of the much vaunted “sophomore surge”. To do so will require Bandt to achieve a herculean swing of 13.84%.

Nor is Bandt likely to secure election on the back of ALP preferences. In order for Bandt to benefit from the secondary preferences of Labor voters, Bowtell’s primary vote would have to fall below that of the (yet to be named) Liberal candidate. This would seem doubtful given the short shrift the Melbourne electorate has shown the Liberals historically.

But Bandt’s campaign is not entirely extinguished of hope. If Bandt can lift his primary vote into the mid 40% range (and the ALP’s primary vote falls slightly also) then he might just be able to get over the line with the help of leaked Liberal preferences.

This is not impossible. Not all Liberal voters will heed the party’s call to preference against the Greens. One third of Liberal voters in the seat of Melbourne at the 2010 state election defied the Liberal’s how-to-vote card instructions and preferenced the Greens ahead of the Labor candidate. If a similar percentage of Liberal voters were to do so at the 2013 federal election, Bandt could receive sufficient secondary preferences to gain election.

The stakes are undoubtedly high for both parties but for Bandt especially because there will be no easy solution to reinstating him using the senate casual vacancy option should he fail in his re-election bid. It is unlikely that one of the sitting Greens Senators will be prepared to martyr themselves on Bandt’s behalf but even if one of them did step aside, there is no guarantee that the fiercely independent state organisations would select Bandt (a member of the Victorian Greens) to replace their Senator.