Labor would have lost two of its seats if the byelections caused by the citizenship debacle had been held in those seats this weekend, a new poll shows, but a key ally of Bill Shorten says there will be no leadership consequences in the event of a political upset.



The Sky/Reachtel poll released on Sunday shows the Coalition has a 52% to 48% over Labor in Longman in Queensland on a two-party-preferred basis.



In the northern Tasmanian seat of Braddon, the poll shows the Coalition has an even greater margin of 54 to 46%, although on a nationwide basis the Turnbull government still lags Labor 48% to 52%.



Labor strategists are worried about Braddon, with the ALP struggling there courtesy of the overhang of the recent state election, which the Liberals won.

One Nation’s performance in Longman will be critical in determining the outcome in the Queensland contest.

But the shadow workplace minister, Brendan O’Connor, told the ABC on Sunday the by-elections were long contests, and the ALP would campaign on their traditional strengths of health and education.

O’Connor said there would be no consequences for Shorten if Labor lost the two seats. “Bill is absolutely secure in his position, he is doing a great job ... I can assure you that the caucus is fully behind Bill Shorten as leader”.

“He brought us very close to an election win when everyone had written us off at the last election, almost in one term, and we are a united, focused opposition, putting forward plans for Australia’s future, whether it be investing in health, whether it’s ensuring that we have a first-class education system, providing tax relief for 10 million workers, looking after aged care”.

Despite the slim lead, the Coalition faces a tough fight in both seats.

Government minister Craig Laundy said the government needed to be “extremely cautious” over the results but is hopeful the government can win.

The by-elections will be held on July 28, alongside those in Mayo in South Australia and Western Australia’s Fremantle, which were also caused by dual-citizenship problems for sitting members.

A fifth by-election in Perth was caused by the sitting member Tim Hammond resigning for family reasons.



On a national level, Labor is still leading the Coalition 52-48 on a two-party-preferred basis.

The poll also found more voters across Australia (49%) backed business tax cuts than were opposed (43%).

In the two seats facing byelections, there was even greater support for corporate tax cuts, according to the poll, with 58% in favour in Longman and 56% in Braddon.

The findings almost mirror those of a Fairfax Ipsos poll in April, which found 49% of voters were in favour of company tax cuts and 44% opposed.

However, a Guardian Essential poll on 22 May in which voters were asked to choose between measures to cut government spending, the single most popular option (60%) was not providing company tax cuts. In total, 45% supported Labor’s tax plan proposal, while only 33% backed the government’s.

A previous Reachtel poll in the prime minister’s electorate of Wentworth in March found two out of three voters wanted the corporate tax rate to stay the same or increase.



And a Guardian Essential poll in February found workers were sceptical that businesses would pass on corporate tax cuts in the form of wage rises, as the government has claimed.