“SNIGGERING” Tories should “watch your backs” before writing off a Labour election victory, Tom Watson fumed yesterday.

Labour’s new deputy leader has divided opinion on whether he will attempt to halt his party’s left-wing shift. But after pipping shadow minister Stella Creasy to victory, he pledged to support his boss “100 per cent.”

Mr Watson secured 39.4 per cent in the first round, and won a majority after two rounds of elimination.

The one-time fixer for Labour’s pre-Blairite right wing has repositioned himself in recent years as an ardent defender of the trade union link. He has also won praise for his confrontations with Rupert Murdoch and paedophiles in the Westminster establishment.

Mr Watson said: “Only through unity comes strength, strength we need to fight the Tories.

“To all those Tories sniggering into their sleeves that we can’t win in 2020 — watch this space, watch your backs.”

Mr Corbyn welcomed the election of his new deputy. “Tom is passionate about holding unaccountable people who don’t wish to be accountable to account,” he said.

“Tom’s your man to do that.”

Some Labour rightwingers hope Mr Watson’s hinterland of moderate positioning and back-room deals will provide a bulwark against flagship Corbyn policies.

Labour First, the right-wing faction most associated with Mr Watson’s previous positioning, welcomed his victory.

Group secretary Luke Akehurst wrote to supporters: “We should note that although we were defeated heavily in the leadership election … Tom Watson made an excellent speech in the closing days of the campaign setting out clear red lines on a strong defence policy and opposition to attempts to make it easier to deselect MPs.”