Day after day in the campaign the prime minister railed against the opposition leader and his union mates.

The Liberal political machine relentlessly took aim at Shorten, with Pauline Hanson doubling down on the attacks.

"Don't let Bill Shorten get a win," the PM told reporters on Saturday in the Tasmanian seat of Braddon.

With Labor holding all four of its seats up for grabs and the Liberals failing to unseat independent Rebekha Sharkie, the focus is now set to fall on Turnbull.

Most worrying for the government will be the 10 per cent swing against the LNP in the Queensland seat of Longman.

A swing of that sort across the Sunshine State would deliver a dozen extra seats to Labor, including that of Home Affairs Minister Peter Dutton.

Not standing candidates at all in Perth and Fremantle may also come back to bite the coalition in a state where Labor's stocks are on the rise.

Labor's key theme in the by-elections was putting "hospitals before the big banks" - a reference to the coalition's proposed corporate tax cut for all-sized businesses.

Setting the tax cut aside could work in Turnbull's favour, but senior government sources are adamant it will be presented to parliament in coming weeks and taken to the election as an essential economic reform.

Turnbull will need to find a way of addressing the issue of health, which almost cost the coalition the 2016 election and contributed to the by-elections result.

School funding will also need to be addressed, given the anger within the Catholic and independent system over what they see are cuts and policy uncertainty.

And voters are stick of what Shorten described as the "Punch and Judy show" of modern politics.

There is a lot of work to be done by the government and time is running out.

Given the by-elections results, and recent opinion polls, all signs are pointing to Shorten being handed the keys to The Lodge within the next 10 months.

Australian Associated Press