After a year maintaining pressure on Prime Minister Malcolm Turnbull, the Opposition Leader’s own future is increasingly the subject of speculation as Mr Turnbull clocks up wins on same-sex marriage and avoids disaster from the dual citizenship scandal.

New polling released today showed a lift in support for the coalition and found 49 per cent of voters would prefer someone other than Mr Shorten to lead the Labor Party.

“This is going to be a very bleak year for Bill Shorten — unfortunately the public have found him out,” cabinet minister Christopher Pyne told ABC radio on Monday.

Mr Pyne was responding to the first Newspoll of the year showing Tanya Plibersek is the preferred Labor leader among all voters, enjoying 25 per cent support, closely followed by Anthony Albanese on 24 per cent and Mr Shorten on 22 per cent.

It’s not a great place for Mr Shorten to be as Labor gears up for the by-election in the Melbourne electorate of Batman, and pressure to clarify the citizenship status of Susan Lamb in the Queensland seat of Longman. But it’s unlikely to be enough to remove him from his position as leader, thanks to a parting political gift left by former PM Kevin Rudd.

Labor will face a tough fight to retain the seat of Batman against the Greens after error-prone MP David Feeney was revealed to be a dual citizen. Unlike other pollies caught up in citizenship dramas such as Nationals’ Barnaby Joyce and Liberals’ John Alexander, Mr Feeney will not be running again in the seat and has been replaced by former ACTU president Ged Kearney as the candidate.

It’s not difficult to understand why. Mr Feeney barely clung on to the seat at the last federal election in 2016 and only managed to secure it because of Liberal preferences.

Greens candidate Alex Bhathal — who has been contesting the seat since 2001 — actually won the primary vote and there’s only a 1 per cent margin separating the two parties.

The Liberal Party also appears to be amping up the pressure with Mr Turnbull indicating the Liberals were unlikely to put up a candidate.

ABC election analyst Antony Green said if the Liberals didn’t run a candidate, the Greens were more likely to win the seat — which would give the Greens its second Lower House seat and dent Mr Shorten’s numbers.

Mr Turnbull said on Sunday the final decision on running a candidate would be up to the Victorian branch of the Liberal Party.

“But I don’t expect we will be running a candidate in the Batman by-election,” he told ABC TV. Asked why, Mr Turnbull said it was a political decision and “parties have to assess priorities and the limited resources”.

Adding to the pressure are comments made by Mr Shorten’s main political rival Mr Albanese, boosting expectations of a Labor win.

“I think Labor can do well in this by-election,” the Labor MP for Grayndler in Sydney’s inner west told Sky News on Sunday.

When asked about his own leadership aspirations, Mr Albanese said he was busy enough in his own portfolio without thinking about challenging for the Labor leadership. But he stopped short of saying he was loyal to Mr Shorten.

“My challenge is doing the right thing by the Australian people as part of Bill Shorten’s team. My loyalty is always to the cause of Labor and the people we represent,” he said.

Political historian Professor Frank Bongiorno of the Australian National University said Mr Shorten would come under increasing pressure if Labor lost in Batman, but it may not be enough to topple him as leader thanks to the rule changes introduced by former leader Kevin Rudd.

Any move against a Labor opposition leader now requires support from 60 per cent of the parliamentary caucus (this rises to 75 per cent if the vote is against a sitting prime minister).

“I think the rules introduced in 2013 — as Kevin Rudd’s parting gesture — are enormously beneficial to Bill Shorten,” Prof Bongiorno told news.com.au.

“There is not doubt he would be under significant pressure now (if the old rules were in place).”

While a leadership ballot is automatically triggered after an election loss, Prof Bongiorno said it was now extremely difficult to remove a Labor leader between elections.

“The rules do provide a degree of insulation for a leader under pressure, which is what they’re designed to do, so you don’t have a bad poll come out, panic occur and a spill. In a sense, the rules are working the way they are designed to work.”

Overall, Prof Bongiorno believes the rule change was a good one — noting this was not a comment on Mr Shorten’s leadership — as he said the bar was set much too low before for removing leaders.

“It was becoming silly. You would have panic over a reverse poll and all of a sudden you have a new prime minister or leader.”

The rules make it very difficult for the Labor Party to remove Mr Shorten even it does lose the seat of Batman.

But Prof Bongiorno is also sceptical the Liberal Party would benefit from a Labor loss in the seat.

“It sets up a potential narrative that the Liberals helped hand the seat to the Greens and I think there’s an issue there,” he said.

Meanwhile Mr Shorten has denied he has an image problem ahead of the release of the latest Newspoll last night.

Mr Shorten said he believed Australians were tired of “gotcha poll questions” and games. “(Voters) want to know what we’re going to do for people. They don’t want to hear us talking about ourselves,” Mr Shorten told the ABC after he was asked if he was worried he had an image problem.

“I think this is the year that if you get the policies right, then the politics will work itself out at the next election.”

— With AAP