Fear and hubris. These seem to be the key driving forces behind budget deliberations as the Australian Parliament careens ever closer to the new Senate configuration on July 1.

Fear of political irrelevancy; fear of voter opprobrium and retribution; delusions of voter apathy and complacency; and over-estimations of voter malleability; each of these self-indulgent forces are shaping the budget that will ultimately impact on Australians’ lives. And in the process sound policy has been relegated to a distant second place.

At this point it’s hard to know whether yesterday’s decision by the Greens to oppose the reintroduction of fuel excise indexation was an act of fear or hubris.

The minor party has learnt well from the demise of the Australian Democrats, as well as their own ill-fated power-sharing experiences with the Gillard and Giddings governments. They know their supporters want the party to stick to principled protest rather than dilute those principles through negotiated outcomes.

And if they need reminding, the Greens have to look no further than the tongue-lashing many supporters gave them after allowing the Abbott Government to abolish the debt ceiling, even though the deal included concessions that improved the transparency of the Government’s decision-making processes.

Greens Leader Christine Milne says one of the reasons her party will oppose the indexation of fuel excise is because it will disproportionately affect those who have no access to public transport. This appeared to be less of a concern in 2011 when the Greens attempted to have the carbon tax imposed on fuel. Milne’s other criticism is that the funds raised will be used to build roads that will result in more congestion. This contention has no basis in fact.

Both justifications are merely a ruse. Now that the deep unpopularity of the first Abbott budget is being confirmed by successive opinion polls, the Greens have more likely concluded there is too much political risk involved in letting budget measures through – even those that accord with their principles – lest they become inadvertently splashed by the waves of voter opprobrium.

But that’s where the matter becomes vexed for the protest party. Given the choice between realising a policy ambition to put a price signal on fuel, considering carbon emissions from transport are the second highest contributor to Australia’s total emissions, and depriving Abbott of a budget win, the Greens chose the latter.

Fear of being seen to be complicit in Abbott’s budget seemingly overrode any motivation to see a version of their policy implemented.

Or was the decision a result of the party’s young guns seeing more political capital to be gained from simple obstructionism than policy purity? This theory aligns with Adam Bandt’s “Bust the Budget” campaign, which is focused on blocking the budget and kicking the Prime Minister out of office by Christmas. It may also be why denials were swiftly issued yesterday to hose down any suggestion that Milne had been overruled by her party on the fuel excise decision.

While a question mark still remains over the Greens’ motivation for opposing the fuel price indexation, there’s no doubt that hubris shaped the budget measure in the first place.

Only a person deluded by pride would assume the channelling of additional funds raised by the increased excise into road-building activities would placate those incensed by the new (albeit small) impost on their cost of living. The same applies to the equally misjudged hypothecation of the proposed GP co-payment to a medical research fund.

The author of those budget measures was being too smart by half, and seriously underestimated the capacity of Australian voters to sense when they are being duped.

Equally, the Prime Minister has been ill-advisedly cocksure in telling Australian voters the fuel excise indexation measure is about road-building, while boasting to US president Barack Obama that it’s a price signal to reduce carbon emissions. Perhaps Abbott thought the internet didn’t stretch as far as the US and those he promised to “axe the tax” would not learn of his defacto carbon tax on transport fuel. A bit less hubris and a lot more fear of electoral consequences might have been the wiser course.

Only Labor seems to have managed so far to withstand the temptation to succumb to the twin indulgences. They’ve declared the ALP will support some budget measures according to merit and alignment with their party’s values.

Unpopular federal budgets have come and gone, but this first Abbott budget could well be remembered as the one that was destroyed from both without and within. If that occurs, fear and hubris will have been responsible for its demise: the over-confidence of those who created it, the fear of those who would be subjected to it, and the political rather than policy motivations of those who tore it down.