On the weekend, I shivered in the rain with a thousand other Melbournians to protest Kevin Rudd's new plan to dump refugees boat-bound for Australia onto Papua New Guinea.

Papua New Guinea is still struggling to fight the consequences of colonialism; corruption and poverty have created conditions in which minorities have to face ongoing violence and hardship; its own government is struggling to prosecute people who torture women for "witchcraft". The Australian government's own travel advisory website cautions Australians that sexual assaults, including gang rapes targeting foreigners, can occur.

And so on election day, I shall be one of many who have Rudd's moral betrayal in mind while their hand prepares to stab a first preference indication on their ballot paper. In my case, that "1" will be for the Greens – a vote executed, this time, with slightly more force than that with which Van Helsing stakes Dracula in a Hammer Horror movie.

Bizarrely, the Greens refugee policies are currently the most traditionally conservative of those on offer from the major parties in this election. They demand Australia simply accord to the UN refugee convention this country signed in 1951; to end offshore processing, meet humanitarian obligations and provide sanctuary to those fleeing persecution. Their policies seek to obey the rule of international law, and are founded on notions of family integrity and community inclusion.

Alternatively, the Rudd government's radical, sudden, forced resettlement of vulnerable people has made me so angry I shall additionally preference the Australian Magical Moonbeam party, The Coalition for People Who Look Like Cats or the Australians For Putting Melons in Their Pants party – if their refugee policies are at all critical of Labor's own. Such are both the promptings of my conscience, and the moral luxury of preferential voting.

But the curse of any voting system is that no matter who you vote for, someone has to get elected. And voting Greens hoping that their leader Christine Milne will be prime minister is comparable to convincing yourself that you've meaningfully moved on from a terrible high-school boyfriend because you've scribbled "I HEART JUSTIN TIMBERLAKE!!!" onto your maths textbook.

Indeed, there are two unpleasant facts outraged Australian progressives must face:

Christine Milne is not going to be the next prime minister

Justin Timberlake will never call

As so, bar an unforeseen health emergency – earwax poisoning, perhaps, or a Speedo-caused rash – the leader of the next Australian federal government is going to be either Rudd or Abbott. And confronted with this dismal choice, my vote shall preference Rudd's Labor party.

This is because while the ALP's policies are morally bad, the Liberal policies are morally atrocious.

The sting of Labor's Papua New Guinea non-solution is that for all its cruelty, the alternative provided by Abbott is not less cruel. The much-touted Liberal party policy pamphlet offers an unsubstantiated promise to "stop the boats", with a vague strategy that consists of bullying the Indonesian government to "do something" while seemingly forcing the Australian navy to keep refugee boats perpetually adrift, Flying Dutchman-like, at sea.

Theirs is as shamefully punitive as Labor's policy, with the inclusion rhetoric of "illegal boat arrivals" included to demonise the entirely legal right to seek asylum even further.

Where communities have voted their displeasure against Labor policies with votes to the Liberals, the consequences of doing so have repeatedly outstripped the original moral complaint. Take the case of the Northern Territory elections, where federal Labor's policy maintenance of the Intervention into Aboriginal communities saw the Country Liberal party (CLP) take the territory legislature with an up to 16% swing in Aboriginal community-based seats.

Where Labor's proposal included retaining police powers to enter homes without warrants and "star chamber" judicial powers like the removal of a right to silence, once elected the CLP actually increased the police presence, axed funding to Aboriginal community social programs and instead plans to invest in alcoholic offender "prison farms".

The pattern of ever-poorer-policy saturates what pages there are of the Abbott's policy booklet. Labor's raiding of projected university funding to pay for their Gonski reforms is bad, but under Howard higher education took a proportionally higher hit, and federal funding for independent schools was made at the expense of the state system that the Gonski funding is trying to repair. Abbott's opposition to Gonski would only make this worse.

On it goes. Where Labor's capitulation to market theory with an Emissions Trading Scheme will not deliver an adequate restructuring of the economy around the issue of climate change, at least Labor admits the expertise of climatologists. Abbott is on record as stating "climate change is crap" and by removing Labor's "carbon tax", his environmental policy amounts to little more than using dole recipients to clear litter.

Where Rudd failed to properly legislate the mining tax, Abbott doesn't believe in one. Where Labor have punished single parents through the welfare system, the Liberals reject welfare even as a basic value.

In a two-party-preferred election, the choice for ethical Australians presents not as between good and bad, but – perhaps more than ever before – between bad and worse.

There are two ways forward through this moral molasses, sticky as it is. The election of the Greens' Adam Bandt and the other cross-benchers to the lower house forced Gillard's minority government to negotiate compromises to remain in power. While government by one of the two major parties is presently inevitable, a humanitarian agenda is possible if first-preference progressive electoral activism restocks the cross-bench.

The second way forward is harder but ultimately more rewarding. The Labor party currently is a party of populist technocrats, not visionaries. The dumping of refugees in PNG is an outrage to morals, but it illustrates how unencumbered by conscience Rudd is to enact policy that secures electoral votes for power.

Progressive Australians have a responsibility to recommit to activism in the social movements that represent our beliefs and build – door to door, person to bloody person – electoral communities around the fights that need fighting. Yes, that means a lot more Saturdays out in the Melbourne rain. But isn't it worth it?

This is a tiny opportunity – one we never had with Howard, and probably never will with Abbott. When Rudd was last prime minister, he opposed equal marriage. Thanks to the hard work of committed activists, a majority of Australians are now in favour of equal marriage – and Rudd supports it.

So, on that note: yo, Justin Timberlake – I'm suddenly single. Call me.