Until last Friday, Mr Abbott had little cause to do much more than parrot the line that he would "turn back the boats'' - unlike the bumbling Labor government, which has presided over a record number of arrivals at Christmas Island this year. The unveiling of Labor's plan to banish all asylum seekers to Papua New Guinea (with no prospect of re-settlement in Australia) changed the political calculus overnight, however. Suddenly it was the Coalition that appeared to be floundering.

In the days since, Prime Minister Kevin Rudd's plan has begun to fray at the edges, not just as a result of criticism from the left, but also because of allegations that detainees on Manus Island have been abused. The outbreak of rioting at a detention centre on Nauru on Friday night was also a reminder that offshore processing sometimes imposes acute psychological strain on those held there seemingly indefinitely. And Mr Rudd's sweetener of substantial additional aid to the Papua New Guinean government has renewed attention on the high price that detaining asylum seekers offshore is exacting on the budget. Nonetheless, Mr Rudd has maintained, not without some justification, that the success of the PNG deal will not be immediately obvious, and that judgment must be reserved.

Labor's resurgence in public opinion polling since the leadership change more or less obliged Mr Abbott to see the Prime Minister's bet. That the Opposition Leader chose to raise it will surprise few people. The credibility of Mr Abbott's pledge to turn around the boats will be bolstered by the greater role accorded the military - and by the advice of retired army Major-General Jim Molan. But a question mark hangs over the tactic nonetheless. As simple as ordering a boat to backtrack to its originating port might sound, the reality could be far more problematic if the passengers disable the engine, scuttle the vessel, or jump overboard. History suggests that asylum seekers are not above such desperate measures.

The template for Mr Abbott's hardline policy is, of course, that which the Howard government embraced after it refused the MV Tampa permission to offload a group of rescued asylum seekers at Christmas Island in 2001. Subsequent to the enactment of the government's Border Protection Bill, however, only four of 12 asylum-seeker vessels were turned back successfully - at a time when traffic was not nearly as heavy as it is now. The legal, diplomatic and moral ramifications of turning back boats remain daunting, and even if the Coalition determines to override all possible objections, there is every possibility that people smugglers would still probe its resolve, just as they have Labor's.

Apart from its pledge to turn boats around and to re-introduce temporary protection visas, little now separates the Coalition's policy from Labor's. An opposition leader more attuned to a longer game than Mr Abbott might have used the opportunity of this "crisis'' to explore a bipartisan approach with Labor. That would have boosted Mr Abbott's credentials as a reasonable and constructive politician - and possibly spared him the political grief that would come his way if the tide of boats continued under a Coalition government. But Mr Abbott has rarely opted for a softly-softly approach when a hairy-chested one was near at hand.