UPDATE SUNDAY NIGHT: Update Sunday night: Phelps has extended her lead to 1,626 votes this afternoon. The correction of errors in two booths identified by Bonham increased her lead to 1,862 votes, while additional postals subtracted. There are probably about 4,000 postals to come by November 2, but Sharma would need about 70% of them to win; he’s currently winning 63.6% of postals. Unless there are further substantial counting errors that assist Sharma, Phelps has very likely won Wentworth.

On Sunday morning, independent Kerryn Phelps leads the Liberals in the Wentworth byelection by a 50.6-49.4 margin, a swing against the Liberals of 18.4% since the 2016 election. Primary votes were 43.0% for the Liberals’ Dave Sharma (down 19.3%), 29.3% Phelps, 11.5% for Labor’s Tim Murray (down 6.2%) and 8.6% Greens (down 6.3%).

Early on election night, it appeared certain the Liberals would lose. After 11pm, pre-poll booths dramatically narrowed Phelps’ margin from 54.4-45.6 to 51.9-48.1. In particular, the Rose Bay pre-poll booth gave Sharma almost 70% after preferences, with over 6,400 formal votes at that booth. Almost 5,200 formal postals then split to Sharma by 64.4-35.6, reducing Phelps’ lead to her current 884 vote margin. Two hospital booths counted Sunday morning also damaged Phelps.

Another 1,266 postals are awaiting processing, and probably another 4,000 will arrive by the deadline for postal votes reception on November 2. If Sharma’s dominance with postals continues, he could win Wentworth after it was called for Phelps early on election night. In byelections, there are very few votes other than postals to be counted after election day; in general elections, Liberals usually perform badly on absent votes.

Analyst Kevin Bonham has identified two discrepancies in election-day booths where Phelps performed much worse on preferences than expected, given primary votes at those booths. If these booths are corrected in Phelps’ favour, she will gain enough votes to offset the postals, but there may be other errors that assist Sharma. Election-night figures will be carefully rechecked over the next few days.

If corrections to the election-night count favour Phelps, she is very likely to win. If there is no substantial correction or corrections cancel out, Sharma is about a 60% chance to win, given his dominance on postals, of which there are probably about 5,000 left to count.

Wentworth has existed since Federation, and had always been held by the Liberals or their conservative predecessors. The loss of Wentworth would deprive the Coalition of its parliamentary majority, and is thus more important than the average byelection, where the government’s majority is not threatened, allowing voters to lodge a protest vote without risking the government.

On early counting figures, there were many media commentators talking about a “record” swing against the Liberals. Bonham said that, though the swings were large, they were not a record even at that time. Talking about a “two party” swing against the Liberals is wrong, because Labor did not make the final two at this byelection.

The Poll Bludger has details of the five Wentworth ReachTEL polls, taken from August 27, three days after the change of PM, to October 15. These polls were conducted for various left-wing groups. In the August 27 poll, Sharma had 34.6% of the primary vote, but recovered to 43.0% on September 27, before slumping back to 33.4% on October 15.

Phelps had 22.5% on September 17, but slumped to 16.7% on October 2, then recovered to 26.3% on October 15. Murray was up to 25.7% on October 2, but fell back to 22.0% on October 15.

Given the disparity between the pre-poll and postal votes and election-day votes, it is likely that polling throughout the Wentworth campaign understated the Liberals’ vote; seat polls are notoriously unreliable. The Liberals’ bad parliamentary week resulted in a worse election-day performance, but pre-poll and postal votes were not as affected by last week.

Media expectations were that if Phelps made the final two, she could defeat Sharma. If Murray made the final two, Sharma would win. As a result, people who wanted Sharma defeated switched to Phelps. The electoral commission will do a two-party count between Sharma and Murray, but probably not for at least two weeks. Sharma will win this count, vindicating the switch to Phelps.

Turnbull’s personal vote was probably worth about ten points to the Liberals in Wentworth. After a large fall following Turnbull’s exit, the Liberals’ primary vote was improving in ReachTEL polls of Wentworth before the events of the last two weeks appeared to push it down again.

Read more: Poll wrap: Worst reaction to midterm PM change in Newspoll history; contrary polls in Dutton's Dickson

On my personal website, I said that the Coalition under Scott Morrison could have problems among better-educated voters, and that Morrison’s social conservatism would not appeal to an electorate that voted Yes to same-sex marriage by an 81-19 margin, the fourth highest vote for SSM in a federal seat.

Electorates like Wentworth have voted Liberal for economic reasons even though they are socially progressive. If the Liberals lose Wentworth, it would be because they had appeared to become too socially conservative and too sceptical of climate change action under Morrison. Phelps was a good fit for Wentworth, being economically conservative but socially progressive.

US midterm elections update

I wrote for The Poll Bludger on Friday about the November 6 US midterm elections. Democrats are likely to win the House, but Republicans are likely to retain the Senate. Trump’s ratings have improved.

Adrian Beaumont does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.