This article was reported by John F. Burns, Don Van Natta Jr. and Alan Cowell, and written by Mr. Burns.

LONDON — Rupert Murdoch’s once-commanding influence in British politics seemed to dwindle to a new low on Tuesday, when all three major parties in Parliament joined in support of a sharp rebuke to his ambitions and a parliamentary committee said it would call him, along with two other top executives, to testify publicly next week about the growing scandal enveloping his media empire.

Mr. Murdoch has been struggling to complete a huge, contentious takeover deal that still needs regulatory approval, the $12 billion acquisition of the shares in British Sky Broadcasting that his company does not already own. In an effort to save that deal from the scandal’s fallout, Mr. Murdoch has already shut down the tabloid at the heart of the scandal, The News of the World. But the accusations have spread to other papers in his News International group, and have taken in an ever wider and more outrage-provoking list of victims.

The House of Commons is scheduled to vote on Wednesday on a motion declaring that “it is in the public interest for Rupert Murdoch and News Corporation to withdraw their bid for BSkyB,” a motion pushed by the opposition Labour Party that the governing Conservatives decided on Tuesday to support. The Conservatives’ coalition partners, the Liberal Democrats, have been vocal in their condemnation of Mr. Murdoch and his executives. With the three parties holding more than 600 of the 650 seats in the house, the motion is expected to be approved overwhelmingly.