There was a moment in Question Time yesterday that was rather telling.

The Prime Minister was in the middle of explaining her proposal to amend the Migration Act. The Opposition was in fits of laughter. For a brief moment - hardly any time at all, really - Julia Gillard adopted the international signal for "I give up".

Arms spread wide, palms and eyes faced heavenward, it was a mute appeal to a deity on whose existence the PM has taken a famously conservative wager.

It was a momentary lapse. Within milliseconds, the Prime Minister had resumed her argument. But her audience was jubilantly impervious.

Two days ago, Julia Gillard threw down an ultimatum to Opposition Leader Tony Abbott: Give me the power to process asylum seekers offshore, or else wear the consequences - either when boats arrive in the coming weeks, or when you are yourself prime minister, and find yourself unable to send people to your own island destination.

Her challenge was an appeal to reason. Not to mention an attempt to "wedge" a political party with claims to have invented offshore processing.

But neither seems to have worked.

Coalition MPs appear increasingly determined to junk the Prime Minister's amendments, and hang the consequences. An air of brash defiance prevails.

Mr Abbott declares that he is not obliged to rescue bad policies devised by bad governments. The best account I could elicit yesterday from Coalition folk was that if they needed help in the future to enact their own border protection policies, they would worry about it when the time comes and not before.

For a party otherwise so committed to stopping the boats, the Coalition was unusually ebullient yesterday at the distinct prospect of their continued arrivals.

And when the Prime Minister was asked a question about the November visit to Australia of the United States president, her answer was interrupted within seconds by the shadow immigration minister, asking her loudly whether she still expected to be prime minister by then.

The rest of the PM's answer was largely obscured by Opposition heckling.

It's difficult enough to come to terms with the fact that a Labor Government, seeking to exile asylum seekers without appeal to a country in which refugees are routinely beaten, is being challenged from the left by a Coalition which claims a nagging concern about human rights.

It's even weirder still to hear a Coalition backbench so overconfident that it would snigger its way through the announcement of a US presidential visit, when 10 years ago it would have considered proscribing anti-US sniggerers as a terrorist group, no questions asked.

As she sat down, Ms Gillard remarked tightly that it was a "disgrace" that the Obama visit had begun in circumstances of such disrespect. She was seen, afterwards, to engage in a rare and markedly hostile exchange with Mr Abbott across the dispatch box, and later on - after Question Time was over - Mr Abbott asked for extra time to declare, most solemnly, his warm support for the presidential visit.

It's hard to locate much angst at all within the Coalition about the Government's ultimatum on asylum seekers. Parts of the Coalition are simply opposed to rescuing the Government. Parts are simply opposed to the Malaysian agreement, and are more relaxed about expressing this opposition than members of Labor's Left. Either way, it adds up to a fairly safe majority for refusing the Government what it wants. And a recipe for dangerous levels of hubris.

One of Australia's most popular political commentators, Annabel Crabb is the ABC's chief online political writer.