It’s the last thing Malcolm Turnbull would want to do, or will do. But what he should do is walk away from the deal he struck with the Obama administration for the US to take refugees from Nauru and Manus Island.

He should then persuade his cabinet to grant a one-off amnesty, and let these people settle in Australia.

It would be a drastic and, for many in the government, a deeply unpalatable course. But the road Turnbull now has Australia travelling – that of the supplicant – is against our national interest. It’s one that sees the unpredictable Donald Trump treating the US’s close ally with near contempt, one that makes the Australian prime minister hostage to the US president’s capricious behaviour.

At the weekend, in their now much-canvassed telephone conversation, Trump told Turnbull it was his “intention” to honour the refugee agreement while, as revealed by the Washington Post’s detailed report, describing it to Turnbull as the “worst deal ever”.

According to the Post, Trump said Australia was seeking to export the “next Boston bombers”; he also told Turnbull “this was the worst call by far” in his round of five phone calls to world leaders that day, which included one with Russia’s Vladimir Putin.

Trump terminated the conversation after 25 minutes – it was expected to run for longer – although Turnbull insists Trump did not hang up on him, but rather “the call ended courteously”.

By Thursday (Australian time), after days of mixed messages from the US administration, Trump was publicly dissing the deal in the strongest terms, tweeting:

No-one can predict where this imbroglio will now go. As one senior Australian source put it: “We are like a cork bobbing on the sea”.

Logic would suggest that Trump would want to ditch “this dumb deal”, which sits at odds with his suspension of the US refugee intake and must look inconsistent to his rusted-on supporters. But equally, he could go the other way and decide there were pluses – in terms of sway over Australia – in keeping it.

If he does proceed with it, the deal could be scuttled in practice by the US “extreme vetting” process excluding most of the refugees. That would leave Australia, after having endured the diplomatic agony, still with responsibility for the people.

What is clear is that the deal has become a big and damaging issue in the Australian-American partnership.

Turnbull has already come under attack for refusing to criticise Trump’s provocative temporary bans on refugees (indefinite for those from Syria) and entrants from seven majority-Muslim countries, which have been widely condemned internationally. Even if he had other motives, his desire to preserve the refugee agreement was obviously one in Turnbull’s approach.

There could be serious longer-term implications if Trump did go ahead with the deal.

Trump is the ultimate transactional politician. If he does something for Australia, reciprocity will likely be demanded at a later stage – with Trump, whose approach is to bully, having no compunction in putting his foot on Australia’s neck. It could be over anything – such as a further commitment to the Middle East or an involvement if the US escalates pressure on China in the South China Sea.

If Turnbull had received a favour, it would be harder for Australia to resist US pressure to do what it might not want to do. Even if the government were comfortable on policy grounds to go along with some US request there would be the suspicion in the public’s mind that this was a quid pro quo.

Apart from those concerns, it is extremely unfortunate to have this issue, with the fractiousness surrounding it, dominate the start of the Turnbull government’s relationship with the new administration. Trump is known for his vindictiveness. If he keeps the deal but angrily and resentfully, that won’t stand Australia in good stead.

Early sourness could limit the extent to which Australia will be in a position to exert any influence on other matters that are of importance to it, such as trade policy – where there are substantial differences between the two countries – and, in particular, America’s future role in the Asia-Pacific region.

Regional countries will be watching closely how the Australian-US relationship unfolds; much of our clout with them derives from the perceived closeness we have with the Americans.

Critics will claim that if Australia cut its losses, dumped the deal and took in the refugees, all manner of disaster would follow.

In particular, they would say, the people-smugglers would start their trade again.

Turnbull on Thursday reiterated that “the only option that isn’t available” to the refugees “is bringing them to Australia for the obvious reasons that that would provide a signal to the people-smugglers to get back into business”.

Yet they didn’t restart their business when the US agreement was first announced, despite suggestions that this could send them an encouraging message.

The government fortified the border further, and the so-called ring of steel around our north would surely be enough to keep boats at bay if it had to take another step. If not, there is something very wrong with our military and coastguard forces.

Politically, there is no question the amnesty course would be extremely difficult for Turnbull, after all the government has said and done.

How difficult? Well, Labor could hardly score real hits against it.

Turnbull would have much more to fear from the conservative ranks in his own party and the right-wing commentariat – and he doesn’t have a lot of gumption when it comes to standing up to these people.

But it would be better to do so, even with the undoubted political risks that it would involve for him, than allow himself and Australia to be subject to the current and future whims of a US president who is raising a great deal of alarm in many places.