By William Schomberg and Michael Holden
LONDON, Dec 7 (Reuters) - Prime Minister Boris Johnson is
heading into Britain's election next week with a lead in opinion
polls, but some of the surveys also suggest that his chance of
winning a parliamentary majority could be too close to call.
Four opinion polls published on Saturday put the lead of
Johnson's Conservative Party over the main opposition Labour
Party at between eight and 15 points, five days before the Dec.
12 national election.
At the lowest end of that range, Johnson cannot count on
winning the majority in parliament he needs to take Britain out
of the European Union by Jan. 31, especially if voters choose to
put aside their usual allegiances to vote tactically over
Brexit.
Polling firm Savanta ComRes said Johnson's lead over Labour
had shrunk to eight points from 10 in a previous poll published
on Wednesday - the tightest margin of Saturday's four surveys.
Its head of politics, Chris Hopkins, said the final few days
of the campaign could be crucial.
"The margins are incredibly tight," he said. "The
Conservative lead over Labour dropping or increasing by one or
two points could be the difference between a hung parliament and
a sizeable Conservative majority."
The election pits Johnson's plan to get Brexit done next
month against Labour's call for a second referendum on a new
Brexit deal under its veteran socialist leader Jeremy Corbyn.
Opinion pollsters were embarrassed by Britain's last
election in 2017, when they under-estimated the size of Labour's
support which cost previous prime minister Theresa May her
majority and threw Brexit into chaos.
They also failed to predict the victory of the Leave
campaign in the 2016 EU membership referendum.
However, one poll, published before the 2017 election, by
YouGov, was more accurate in predicting the number of seats won
by each party.
Known as an MRP poll - an acronym for its Multilevel
Regression and Post-stratification model - it predicted 93% of
results in individual constituencies correctly.
The Sunday Times said a poll by Datapraxis, also using the
MRP model and based on 500,000 online interviews, predicted that
Johnson would win a majority of 38 in parliament next week, down
from a projection of 48 two weeks ago.
"We have never seen as many undecided voters this late in
the campaign," Datapraxis boss Paul Hilder said. "As many as
80-90 constituencies are still up for grabs. A much larger
Conservative landslide is still possible - but so is a hung
parliament."
YouGov said last month that its MRP model suggested the
Conservatives were on course for a majority of 68. YouGov will
publish an updated version of the poll on Tuesday.
Best for Britain, a group that wants a second referendum to
stop Brexit, said an MRP poll it commissioned showed Johnson was
on course to win 345 seats in parliament - or a majority of 40 -
without tactical voting, a term for when people back parties
they do not usually support in an attempt to defeat others.
But tactical voting by 41,000 voters in just 36 swing seats
could prevent Johnson from getting a majority, it said.
"This election is on a knife-edge," the group's chief
executive Naomi Smith said. "If enough remainers hold their nose
and vote for the candidate with the best chance of stopping the
Tories (Conservatives) in their seat we're heading for a hung
parliament and a final say referendum."
(Reporting by Michael Holden
Editing by William Schomberg and Daniel Wallis)