Undecided Voters Matter: Theresa May’s Lead Over Jeremy Corbyn Might be Only Single Digits

Poll numbers from the initial days after British Prime Minister Theresa May’s triggering of snap elections for June 8th were perhaps even more dire than hankerers after New Labour could have prayed. Corbyn-led Labour started off the campaign with headlines, based on data from multiple scientific polling firms, blaring out their twenty some point deficits to May’s Conservatives. While even those numbers should be considered deceiving, a consistent drum beat of better news from many of the same pollsters – with the numbers read more accurately – suggests May’s lead could have shrunk to single digits already with plenty of time and room for further Labour growth.

Without getting into the weeds too much, there is a simple problem with most of the headlines and even the few poll aggregators active to date in the United Kingdom election cycle. Like the poll aggregators and data experts who gave Hillary Clinton far better chances than even Nate Silver and FiveThirtyEight, insufficient attention is being paid to the huge number of undecided voters recorded by nearly every pollster. (See Silver’s “The Invisible Undecided Voter” from January 2017. As a side note, our final analysis here of the November 8th U.S. election was more accurate on both a national and state by state level than FiveThirtyEight’s. FiveThirtyEight was generally more accurate for the Democratic Primary cycle.)

Could Corbyn pull-off another Brexit or Trump-style shocker? We will not know for five more weeks, but what we do know should give succour to electorally minded leftists while causing serious trepidation to supporters of May and backers of former Prime Minister Tony Blair’s ongoing tantrum around the elevation of Corbyn.

Here, in one chart, is May’s lead over Corbyn from all scientific polling to date with and without undecideds included:

May Corbyn Chart 1

By simply removing undecided voters from the calculus, the numbers used by most media outlets artificially inflate May’s numbers by five points. This happens because the net result works to assign undecideds to the parties according to their numbers strength otherwise in the polling data. Roughly speaking, on average, in the data above May’s Conservatives are assumed to garner just under two undecided voters for every one assigned to Corbyn’s Labour.

But is this a fair assumption?

Not in the least based on the data that we do have. As with Trump’s initial soft support in the U.S. elections, there are far more Labour voters from 2015 who are considering not voting for Labour this time around. Perhaps they will stay away or vote for another party, but just as Never Tump voters, Bernie or Busters, and 2008’s PUMAs (Party Unity My Ass supporters of Hillary Clinton), the overwhelming majority of party loyalists disappointed in the primaries or leadership races do eventually wind up coming home by election day. Indeed, the clear data we have to date from YouGov polling, for instance, shows that this explains much of the gap Corbyn has already closed. Eighteen percent of 2015 Labour voters were undecided in the first full YouGov poll [pdf] after the elections were called (versus just 12% for 2015 Conservative voters). That same number fell to just 11% for Labour for the two YouGov polls in the field April 25-28th [pdf], while falling just a tick to 10% for Conservatives.

Over the course of those same three polls, May’s lead over Corbyn, including the undecideds fell from 16% to just 8%, not very far off from the results (a 6.6% Conservative advantage) of the 2015 election. Meanwhile, the trendlines are all pointing toward continued tightening in Labour’s favour. All four pollsters (YouGov, ICM, ORB, Opinium) with multiple polls out since April 18th have seen Corbyn inch closer with each new poll.

Clustering the polls by date (with undecideds included) over the first week and a half of the campaign, we see that May’s large lead is far from stable . ICM’s poll out yesterday shaved another point off May’s lead. If the polls that join ICM in making up the next cluster follow this pattern, we are likely to have an average of recent polls in the single digits.

UK #GE2017 Chart 1

If this trend continues, the Conservative majority in parliament may look very similar to what it has been since 2015.

More troubling for May’s Conservatives, not all of this lead shrinkage can be chalked up to undecided Labour voters moving to the Corbyn column. May also looks to be bleeding support. She could, in fact, end up with no majority at all.

More articles by:

Doug Johnson Hatlem is best known for his work as a street pastor and advocate with Toronto’s homeless population from 2005-2013. He is now a film producer and free-lance writer based in Chicago.

Weekend Edition
March 23, 2018
Friday - Sunday
Roberto J. González
The Mind-Benders: How to Harvest Facebook Data, Brainwash Voters, and Swing Elections
Paul Street
Deplorables II: The Dismal Dems in Stormy Times
Nick Pemberton
The Ghost of Hillary
Andrew Levine
Light at the End of the Tunnel?
Paul de Rooij
Amnesty International: Trumpeting for War… Again
Jeffrey St. Clair
Roaming Charges: Coming in Hot
Chuck Gerhart
Sessions Exploits a Flaw to Pursue Execution of Meth Addicts
Robert Fantina
Distractions, Thought Control and Palestine
Hiroyuki Hamada
The Eyes of “Others” for Us All
Robert Hunziker
Is the EPA Hazardous to Your Health?
Stephanie Savell
15 Years After the Iraq Invasion, What Are the Costs?
Aidan O'Brien
Europe is Pregnant 
John Eskow
How Can We Live With All of This Rage?
Matthew Stevenson
Why Vietnam Still Matters: Was Khe Sanh a Win or a Loss?
Dan Corjescu
The Man Who Should Be Dead
Howard Lisnoff
The Bone Spur in Chief
Brian Cloughley
Hitler and the Poisoning of the British Public
Brett Wilkins
Trump Touts $12.5B Saudi Arms Sale as US Support for Yemen War Literally Fuels Atrocities
Barbara Nimri Aziz
Iraqi Landscapes: the Path of Martyrs
Brian Saady
The War On Drugs Is Far Deadlier Than Most People Realize
Stephen Cooper
Battling the Death Penalty With James Baldwin
CJ Hopkins
Then They Came for the Globalists
Philip Doe
In Colorado, See How They Run After the Fracking Dollars
Wilfred Burchett
Vietnam Will Win: Armed Propaganda
Binoy Kampmark
John Brennan’s Trump Problem
Nate Terani
Donald Trump’s America: Already Hell Enough for This Muslim-American
Steve Early
From Jackson to Richmond: Radical Mayors Leave Their Mark
Jill Richardson
To Believe in Science, You Have to Know How It’s Done
Ralph Nader
Ten Million Americans Could Bring H.R. 676 into Reality Land—Relief for Anxiety, Dread and Fear
Sam Pizzigati
Billionaires Won’t Save the World, Just Look at Elon Musk
Sergio Avila
Don’t Make the Border a Wasteland
Daryan Rezazad
Denial of Climate Change is Not the Problem
Ron Jacobs
Flashing for the Refugees on the Unarmed Road of Flight
Missy Comley Beattie
The Age of Absurdities and Atrocities
George Wuerthner
Isle Royale: Manage for Wilderness Not Wolves
George Payne
Pompeo Should Call the Dogs Off of WikiLeaks
Russell Mokhiber
Study Finds Single Payer Viable in 2018 Elections
Franklin Lamb
Despite Claims, Israel-Hezbollah War is Unlikely
Montana Wilderness Association Dishonors Its Past
Elizabeth “Liz” Hawkins, RN
Nurses Are Calling #TimesUp on Domestic Abuse
Paul Buhle
A Caribbean Giant Passes: Wilson Harris, RIP
Mel Gurtov
A Blank Check for Repression? A Saudi Leader Visits Washington
Seth Sandronsky
Hoop schemes: Sacramento’s corporate bid for an NBA All-Star Game
Louis Proyect
The French Malaise, Now and Then
David Yearsley
Bach and the Erotics of Spring