Malcolm Turnbull has foreshadowed personal income tax cuts for middle-income Australians in a speech to business leaders in which he has attempted to shrug off the chaos of the past few months and make the case for his “measured” leadership.

The prime minister used a speech to the Business Council of Australia to hint income tax cuts were under active consideration and to declare the rolling citizenship debacle had proved the strength of the Australian parliament, not underscored its “frailties”.

Turnbull said persistent political uncertainty, amplified by mainstream media outlets adopting the “hyperbolic outrage and sensation of the Twittersphere”, had made the case for his own “calm” leadership. Recent events, he contended, had underscored the need for “a steady hand at the helm”.

Turnbull’s public projection of his serenity during challenging political times on Monday night followed the government’s decision earlier in the day to cancel one of the two remaining parliamentary sitting weeks in the lower house – a decision that immediately sparked political uproar.

The cancellation is a clear attempt to minimise the risks the government will face in the lower house now it has lost its working majority, with Nationals publicly threatening moves to establish a banking inquiry in defiance of government policy and with a raft of citizenship declarations from MPs likely to result in either more resignations or referrals to the high court.

Conservatives, including the treasurer, Scott Morrison, are also publicly positioning for battle during the looming parliamentary debate to legalise same-sex marriage, facing off against Turnbull’s publicly stated desire that Dean Smith’s private member’s bill proceed with only a minimum of amendments.

The manager of government business, Christopher Pyne, said on Monday the cancellation of the sitting week had not been prompted by renewed threats from Nationals on the banking inquiry – but because the government was running ahead of schedule, because it had been “very effective, very efficient”.

Pyne said the shift was to enable a focus on marriage equality and the citizenship issues, and to give the Senate opportunity to resolve the marriage bill.

While Labor and the Greens are threatening to turn up to work in Canberra next week in defiance of the cancellation, Pyne declared the move a “stunt” and said opposition MPs would not be able to claim travel allowance for “gaming the system”.

With a fresh bout of partisan uproar dominating Monday, the prime minister told his business audience that the government would overcome its challenges with “calm, composure, deliberation” – qualities, he said, the government had exhibited since winning the election by only one seat.

While the government’s woes on a range of fronts have dominated the headlines over a challenging political year, Turnbull said 2017 had been a year of delivery, “focusing on what matters to Australians” like employment, energy policy and boosting business conditions.

The prime minister pointed to improvements in unemployment and business conditions over the course of the year.

Turnbull said the government had “delivered solutions to intractable problems that have confounded previous governments, including school funding and energy reform”.

The prime minister said the government was committed to lowering business taxes, because “if we don’t reduce our corporate rate to 25% as planned over the coming decade, the only advanced nations that will exceed Australia are Japan and Malta”.

But he said the Coalition would not stop there. “In the personal income tax space, I am actively working with the treasurer and my cabinet colleagues to ease the burden on middle-income Australians, while also meeting our commitment to return the budget to surplus.”

Turnbull said tax cuts would boost efforts to address cost-of-living pressures, like measures the government had taken to reduce power bills, the budget’s housing affordability measures, childcare reforms and an overhaul of private health insurance.

“Another way of putting more money into people’s pockets is by increasing their disposable income through lower taxes,” Turnbull said.