Theresa May set for first by-election victory after disastrous poll reveals THIRD of Labour voters in Copeland are deserting Jeremy Corbyn

THERESA May is set for her first by-election victory after disastrous polling revealed almost a THIRD of Labour voters in Copeland are deserting Jeremy Corbyn.

Sources claim canvas returns show that just 70% of those who voted for the party at the 2015 General Election will plug for them again in the crunch by-election next week.

The Tories are so confident that the Prime Minister will make a personal appearance to the Cumbrian constituency dominated by the Sellafield nuclear plant later this week.

Bookies are pricing the Tories at 4-9 odds on for a victory.

One Westminster insider said: “The Tories have got Copeland in the bag. Everyone in the Cabinet has been up there. They’re throwing everything at it.”

The claims came as Labour equalled its lowest level EVER in nationwide polls – just 24 per cent. YouGov said the Tories now had a 16 point lead UK-wide.

The canvas returns in Copeland come from conversations on the doorstep in the constituency.

Some suggest up to 33 per cent of Labour’s 2015 vote in the constituency has switched – largely to the Conservatives.

The by-election was triggered by the resignation of Jamie Reed before Christmas. He took the seat in 2015 with a 2,564 majority from the Tories.

Conservative campaigners have played on Jeremy Corbyn’s anti-nuclear views in an area where 20,000 jobs rely on a planned new nuclear plant near to Sellafield.

Labour picked a former ambulance driver Gillian Troughton to contest the seat who vowed she was pro-nuclear “no ifs, no buts”.

Sources claim the situation was so bad Labour were now devoting “all the resources they have” to a separate by-election in Stoke – where the party is up against UKIP leader Paul Nuttall.

Labour’s new campaign chief Ian Lavery on Sunday insisted that it would only be a “hiccup” if the party lost in Copeland and Stoke.