Former PM Malcolm Turnbull has weighed in on the Liberal leadership turmoil, saying the party has abandoned the centre for an ideological “la la land” – and refusing to endorse expected challenger Angus Taylor.

“I sympathise with all of my former colleagues. They are in a terrible state. The Liberal Party is facing an existential crisis,” Turnbull said on a visit to Canberra on Tuesday.

“This is the inevitable consequence for the Liberal Party of imagining that the goal of politics is to seek the approval of the Sky News audience.

“That may well represent many of the members of their branches, but it does not represent Australia.”

Taylor is widely expected to attempt a leadership change by the end of the week after a string of dire polls showed plummeting voter support for the Coalition.

The opposition defence spokesman believes he has the numbers to win a spill, but logistical challenges mean party members are unlikely to vote until Thursday night or Friday as senators are tied up in parliamentary committee hearings before then.

Turnbull said Taylor should be open about his intentions in a possible challenge against Sussan Ley.

“I think it is important to stand up and be counted. This is a place where we vote in public,” he said.

“If Angus wants to be leader of the Liberal Party, he should stand up and say so, and say why.”

But, asked if Taylor was fit to be leader, Turnbull was less enthusiastic.

“He is absolutely fit to be leader, because the only qualification for being leader of the opposition is to be member of the House of Representatives,” he said.

Earlier on Tuesday, leading conservative Liberal senator Jonno Duniam urged Taylor to effectively put up or shut up.

“If Angus is interested in… the leadership then he should say so,” Duniam said.

“That’s something he needs to make clear. Then what events take place after that well-trodden path? That’s all a matter for him.”

Party conventions require any frontbencher who wants to challenge for the leadership to resign from the shadow ministry.

Taylor is yet to do so, despite admitting to conversations with his colleagues about the Liberals’ future direction.

Duniam also warned a change in leadership wouldn’t be a silver bullet – a sentiment echoed by pollster Kos Samaras.

“The antidote to their problems is not the leader,” the Redbridge Group director and former Victorian Labor strategist said.

“It would be good policy, and that’s a long road ahead of them and isn’t an easy solution.”

The latest Newspoll for The Australian, conducted during the most recent break-up between the Liberals and Nationals and released on Sunday, put the Coalition’s first-preference vote at just 18 per cent, eclipsed by One Nation on 27 per cent.

Samaras doubted the Coalition could develop robust policies before the 2028 election while also competing with One Nation.

“They are not only declining in support in regional Australia to One Nation, they’ve historically been losing ground to the Labor Party and to independents,” he said.

“Outside of Queensland, they only hold five urban seats among a cluster of voters to the tune of 14.5 million. So they’ve got a lot of problems.”

To arrest the slide in the polls, some Liberals have called for a greater focus on policy development.

“We can talk about leadership until the cows come home, but that is not going to be what Australians look at and go, ‘they’ve got the message, we’re on track again’,” Duniam said.

Fellow Liberal senator Andrew Bragg, who is from the moderate faction, said housing and migration policies needed to be the focus.

“Politicians are well paid, they’re sent to Canberra to do policy work and to hold the government to account,” he said.

“We are in control of our own destiny, and we will be even more so if we are forthright on policy.”

-with AAP