For politicians, the uncertainty of continued popularity or success is an occupational hazard, and Mr Turnbull will doubtless take this dip in fortunes in his stride. But if anyone had sought to predict back in September where and when the incoming prime minister might stumble, few would have cited caution and inactivity.

On the eve of his successful challenge against Tony Abbott, Mr Turnbull promised a new style of leadership which respected people's intelligence and which was capable of making "tough calls and tough decisions". In his first major economic address as on November 5, he announced that all options for tax reform were "back on the table" – including an increase in the GST – and that the government would take a reform package to the next election which would not only raise the revenue needed for budget repair but ensure the tax burden was shared fairly across the community.

Despite Mr Turnbull's hopes for a sensible and adult "conversation", the intrusion of self-interest and bloody-mindedness was not long in coming. Some of shrillest voices ranged against changes to the GST, negative gearing, and superannuation concessions have been from the government's own backbench, although the usual vested interests have been loudly insistent as well. There's little doubt some of this intransigence within the Coalition is motivated by ideology as well as animus toward Mr Turnbull. Indeed, the most prominent defender of the status quo has been Tony Abbott, apparently still in denial about the reasons his party room rejected him.

The alacrity with which Mr Turnbull has caved in to demands to take GST and negative gearing off the table suggests a certain sensitivity about his authority within the party, or lack thereof. Leaders have a duty to take the pulse of their backbench on important issues, but in being so agreeable, so quickly, to their demand on tax reform, Mr Turnbull's standing in electorate has probably been diminished. And it will be diminished further if speculation about an early election proves correct.

When Mr Turnbull was asked in September about an early poll, his near unequivocal response was that he expected the government to serve its full term. That has remained the Prime Minister's line ever since, though with rather less conviction of late. Indeed, speculation is building that Mr Turnbull will call a double dissolution election for July now that Parliament is close to approving Senate voting changes that will probably see the removal of the crossbenchers who've proved so hostile to the Coalition's legislative agenda. But because a double dissolution election must be called no later than May 11, the budget will have to be brought forward, leaving barely a week for parliamentary debate and public discussion.

In calling an early election for what may be regarded as cynical reasons, Mr Turnbull runs the risk of damaging his credibility as an economic reformer intent on getting the process underway sooner rather than later. And Mr Turnbull's ability to shape and implement major economic reform will likewise be weakened if public anger over an early poll results in the government's majority being reduced to any significant degree. No prime minister ever willingly narrows his election date options. However, the arguments in favour of a July 2 election do not look compelling, and Mr Turnbull should resist the temptation.

Mr Turnbull's current travails are in part a consequence of his failure to manage expectations and his inability to keep a reasonably tight control on the tax debate, itself a consequence of his decision to allow Scott Morrison to make the running. The tax statement promised before the budget offers Mr Turnbull a way back to credibility, but unless the distraction of an early election is ruled out, the opportunity is likely to be lost.