The British political establishment rose up against Rupert Murdoch on Tuesday, seeking to kill his attempt to buy full control of British Sky Broadcasting, just as the News Corp chairman moved to appease investors with a $5bn share buy-back plan.

The decision by the UK’s Conservative and Liberal Democrat coalition government to support an opposition motion, which will today call for Mr Murdoch to withdraw his largest ever takeover bid, further reduced the media mogul’s chances of salvaging the deal.

“I think he must be thinking of pulling the bid, if not tonight, then after the debate tomorrow,” said one person who has previously worked closely with Mr Murdoch on strategy and acquisition. “It is a quite remarkable outcome of all this that Rupert Murdoch has no one who will speak up for him in the House of Commons. A fortnight ago he had a cabal that had the ear of everyone in government.”