A Pollster’s Warning for Boris Johnson

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(Bloomberg Opinion) -- Once upon a time, elections in the U.K. were relatively uneventful. For decades after the war, power would alternate between the Labour and Conservative parties, each with a substantial base, as swing voters switched sides and competitive districts mirrored changes in the national popular vote.

The next election, which now seems unavoidable before the end of 2019, comes with more uncertainty than any other in recent times. Naturally the roots of this are in Brexit and its impact on politics more widely. But what makes this election so different is the way this uncertainty manifests itself in so many moving parts.

First is the political backdrop itself: a government with no majority pursuing a policy that represents radical change and one that’s engaged in a standoff with parliament. Prime Minister Boris Johnson has chosen to interpret the 2016 Brexit vote as a mandate to leave the European Union without a deal if the EU doesn’t bend to the U.K.’s demands. Most MPs are opposed to a no-deal exit. What’s going to happen, and what effect it will have on voters, is hard to game, although the 2017 general election – during which former Prime Minister Theresa May squandered an enormous lead in the polls to lose her party’s majority – showed how much things can move during a campaign.

And things – or rather, people – have been moving even before the campaigning this time. This week alone has seen two members of parliament cross the floor of the House of Commons and Johnson suspend 21 of his lawmakers for voting against the government. Several have announced their retirement (as has Johnson’s brother Jo, who resigned Thursday), but others may stand against their former party, potentially making a number of normally uncompetitive races much closer.

How accurate are the polls? Surveys this year have shown consistent systematic variation between pollsters, known as “house effects,” depending on the methodology, with some currently showing big Conservative leads and others showing it much closer. Quite a lot rides on whether the reality is closer to the former than the latter.

Pollsters have been working very hard to improve their methods. But the environment of electoral flux makes our job far harder and in that sense isn’t unlike 2015, when polls suffered their biggest miss in a generation.

And the U.K. is tough to poll at the best of times: turnout is relatively low, having not exceeded 70% since 1997. The winner-takes-all electoral system magnifies the effect of polling errors. A percentage point change in the popular vote usually shifts far more than 1% of seats.

Even if we knew the popular vote with certainty, there is an awful lot that isn’t knowable, not least because converting vote shares into seats is not straightforward. In 2017, we already saw a variety of swings, with areas that strongly backed Brexit swinging towards the Conservatives, while those that opposed it heavily swung against them.

Although poll numbers have normalized somewhat since the four-way split seen shortly after the European elections, when pro- and anti-Brexit votes consolidated around the Brexit Party and Liberal Democrats respectively, the combined vote share of Labour and the Tories remains very low, averaging under 60% in recent polls, compared with almost 85% at the last election.

As a consequence, some very strange and lopsided seat results are possible if the votes shake out the right way. The chances of the most extreme outcomes have receded, but a surge for either the pro-remain Liberal Democrats or the Brexit Party, which supports leaving the EU without a deal, during a campaign could bring those outcomes back into play.

While there are, as yet, no formal alliances along Brexit lines, there is still time. Even without them, there could be a lot of scope for tactical voting, where a relatively small but decisive proportion of the electorate switches from their preferred party to back one with a better chance of winning in their district.

The potential impacts of both formal alliances and tactical voting was illustrated at last month’s special election in Brecon and Radnorshire. Four smaller pro-Remain parties stood aside in order to help defeat the Conservatives, giving the Lib Dems a narrow victory.

But the Tories also achieved a substantial “Boris bounce,” consolidating the Leave vote at the expense of the Brexit Party. A similar squeeze in a general election could be significant given that, as a new party, the Brexit Party’s ground game is considerably weaker than Tories.

If we’re going to talk geography, we can’t ignore Scotland, where Conservative seat gains in 2017 made the difference between keeping power and losing it. Polling suggests they are under threat. The resignation of the Tories’ popular Scottish leader Ruth Davidson will not help their cause.

And lastly, it’s worth bearing in mind the impact of the politically homeless. We hear a lot about traditional Labour voters in rust belt areas of central and northern England that backed Brexit. They continue to matter, particularly if they switch party of stay home.

But there are other groups. What about affluent suburban voters most concerned about the economy, who prefer a boring, fiscally conservative government, and are nervous about a no deal Brexit? Or those whose preference is one of the minor parties that won’t end up standing in their area?

Johnson and his party start off in the better position, ahead in the polls. Yet there has never been a U.K. election with so much uncertainty from so many sources. This one will be high stakes for everyone.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Matt Singh runs Number Cruncher Politics, a nonpartisan polling and elections site that predicted the 2015 U.K. election polling failure.

©2019 Bloomberg L.P.

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