No one can reasonably accuse Barack Obama of faintheartedness. Whatever the enterprise in hand, he tries, tries and tries again to implement the policies he was elected on. We saw the months and the attention he applied to remaking US policy in Afghanistan, to the point where he was reproached with over-intellectual dithering. We are now witnessing, one more time, his Herculean efforts to persuade Congress to pass a healthcare reform that will really help uninsured, or underinsured, Americans.

Mr Obama's decision to postpone a planned visit to Indonesia and Australia, so as to oversee a new stratagem for passing the necessary legislation, is the latest proof of his commitment to this cause. But his readiness to risk a certain amount of diplomatic damage in Asia also hints at how much else is at stake. The passage of healthcare reform may not be quite the make-or-break moment for his entire presidency that some, not least his Republican opponents, would like it to be, but its fate will convey a message about his strength – or weakness.

He needs the reforms to pass; just as much, though, he needs them to be more than a formality. As Hillary Clinton could have told him, any change to US healthcare designed to benefit those excluded from the established system calls forth a ferocious and variegated alliance. There is the majority of Americans who have acceptable health insurance at present; there are pensioners who (though they are loath to admit it) benefit from a generous state-funded system, and there is a host of well-funded interest groups, from doctors to insurance companies.

All of them fear a loss of benefits or remuneration if insurance is extended to people who – as they see it – are poorer, less healthy and less responsible than they are. The social justice argument does not sway them; it is dismissed as European-style socialism that will come back to bite the hard-working majority in their taxes.

Mr Obama has had particularly bad luck with healthcare reform, the death of Senator Edward Kennedy last August being a particular blow. No sooner had the Senate passed its bill – paving the way for the two Houses to reconcile their versions into a law for the President to sign – than the Democrats lost their legislative majority in the upper chamber, by dint of losing the late Senator Kennedy's seat to the Republicans. That reflected extraordinary carelessness on the part of Massachusetts Democrats. With mid-term elections looming later this year, the decision of Senate Republicans to press their unexpected advantage was entirely predictable.

While bad luck played its part, however, the troubled healthcare saga has also exposed some of Mr Obama's weaknesses. Not as adept at backroom Congressional politics as either Bill Clinton became or George Bush already was, he has struggled to get his way with the legislature. Nor, for all the rhetorical gifts he displayed on the campaign trail, has he been able to use the President's bully pulpit to optimum effect.

There is no reason why, with time, Mr Obama should not manage Congress as effectively as his two predecessors. What is more, he goes into what it must be hoped is the healthcare endgame this weekend, with an additional argument. Backed by the Congressional Budget Office, he says that the Democrats' plan will also cut the budget deficit, thereby delivering a double benefit. This should make it harder for Congressional Republicans to resist – but, by itself, probably not hard enough.