Yet when the moment was ripe, Turnbull had no hesitation in deciding to strike against Abbott. Prime Minister Malcolm Turnbull in his Parliament House office. Credit:Andrew Meares Again on Monday we saw that he is entirely capable of choosing his moment to make very bold decisions, but they are not necessarily conventional ones. "Malcolm didn't build a business empire by playing by conventional rules", the independent senator Nick Xenophon remarked on hearing the Prime Minister's announcement. Turnbull silently endured weeks of dismissive commentary branding him a hopeless ditherer as he arranged the plan he unveiled on Monday.

From hopeless ditherer to decisive leader in a moment, Turnbull has now staked his government on a challenge and put all the other political parties on the defensive. And while it's high stakes, for Turnbull it's actually low risk. Why? He has issued a challenge to Labor, the Greens and the independent senators to join the government in a Senate vote to impose law and order in the construction industry. The strong-arm union in the industry, the CFMEU, has gone rogue and the government is intent on taming it. The government has a bill before the Senate to reintroduce a specialised federal regulator, the Australian Building and Construction Commission. The ABCC was created by the Howard government and dismantled by Labor.

The Senate has already rejected the bill once. Labor and the Greens are intent on protecting the CFMEU, a major donor and client of both parties, and some of the Senate independents voted with them. By asking the Governor-General to prorogue the Parliament and then bring back the Senate to deal with this specifically, Turnbull has put maximum pressure and maximum scrutiny on the Senate. If the Senate refuses, Turnbull has promised to dissolve both houses of Parliament and take the country to an early election to get his way. If it buckles, he will let the Parliament run its normal three years and call a customary general election - for the House and half the Senate - in September or October. Turnbull figures he can't lose. If the Senate agrees, he gets his way and he is seen to be a strong, determined leader. The Senate crossbenchers will hesitate to frustrate him again.

If the Senate refuses, Turnbull calls a double dissolution election which, on the current outlook, he would win handily. He would then hold a joint sitting of both houses to legislate the bills. Again, he gets his way. Why did Turnbull keep it so secret? Because he wanted to get the Senate to agree to change the rules for voting for senators first, something that only happened last Friday. The new rules make it much harder for the independents in the Senate, other than Xenophon, to be re-elected, so this intensifies the pressure on them to buckle to Turnbull now. If word had leaked of Turnbull's jihad against the CFMEU, the Greens would not have cooperated on Senate voting reform. And as this plays out in the months ahead, it neutralises Turnbull's most lethal enemies – the internal ones, Tony Abbott and his small core of conservative malcontents.

Because the entire Coalition is united in the cause of taming the unions generally and the CFMEU particularly. It's an issue that will mobilise the business sector behind the government, too. And it will leave Labor and the Greens defending lawlessness in the construction industry. And, on the policy issue itself, it's an industrial relations matter but also an economic reform. Construction is the country's third biggest industry, bigger than the mining sector, and an important enabler for all the industries that need buildings. This fits neatly within the overarching theme that Turnbull will take to the election. Together with the tax changes he plans to introduce in the May budget, he will campaign on economic leadership. Turnbull and the Coalition already have a strong lead in the polls in the public's perception of economic management.

His protracted Senate showdown gives him an ideal mechanism to keep the national debate on the government's favoured ground. Turnbull has yet to prosecute his case with the voters, but he has now taken control of the agenda, wrongfooted the other parties and asserted himself as a decisive leader. Enjoying the reaction to his bombshell announcement on Monday, Turnbull observed to colleagues that the Canberra press gallery had been wrong-footed into thinking him a hopeless ditherer: "Just because the press gallery doesn't know what I'm doing doesn't mean that I don't know what I'm doing." Follow us on Twitter