Scott Morrison and the Coalition enter the final parliamentary sitting weeks of 2018 trailing Labor by 10 points, and with a primary vote of 34%.

The latest Newspoll, which translates to a 20-seat loss for the Coalition if an election were held today, follows a rout for the Liberals in the Victorian election at the weekend, with voters in Melbourne’s conservative-leaning eastern suburbs deserting the Liberals and returning the most progressive government in the country for another term.

Labor is ahead of the Coalition on Newspoll’s two-party-preferred measure 55% to 45% in the latest survey, which is a weaker result than last week’s Guardian Essential poll, which had the ALP ahead of the government 52% to 48%. Labor’s primary vote in Newspoll is 40%.

While the poll indicates the Coalition is facing an electoral drubbing, and suggests the leadership change in August has harmed the government’s political position, Morrison’s indicators are holding up.

The prime minister’s approval rating is up four points in a fortnight, and his disapproval down five. Morrison also remains ahead of Bill Shorten as preferred prime minister on 46%, up four points, to Shorten’s 34%, down two.

The government goes into the final sitting fortnight of the year having lost its majority in the lower house. Morrison has entered into a stability deal with the Queensland maverick Bob Katter to try and bolster the government’s position.

But with the crossbench emboldened, signalling it will pursue its own agenda, pressuring the government to create a federal anti-corruption commission and also expedite the removal of vulnerable asylum seekers on Nauru, the Morrison government faces a challenging end to the parliamentary year.

The government has a packed program in December before the summer holidays, with the looming sitting fortnight, and Morrison due to attend the G20 meeting at the end of this week.

The prime minister will meet premiers and chief ministers at a Council of Australian Governments meeting in Adelaide, with an agenda ranging from population policy to a refresh of closing the gap.

The government also has to deliver the midyear economic review, expected mid-month, and make a number of critical decisions, including whether to go through with a controversial Middle East policy reboot which has stirred up diplomatic tensions in the region, and also determine the next steps for the Snowy Hydro 2.0 project.

The former prime minister Malcolm Turnbull will also be in the public spotlight with an energy speech in early December, an outing that follows his recent observation that the Liberal party was unable to deal with the challenges of climate change.