More than 50 British MPs say they will back a parliamentary motion urging the BBC to screen a charity appeal for Gaza.
The BBC says broadcasting the Disasters Emergency Committee film would put its reputation for impartiality at risk.
Criticism over the corporation's decision has come from archbishops, government ministers, charity leaders and 11,000 viewers.
The Archbishop of York, Dr John Sentamu, said the committee was asking for relief and it was not an appeal by the Palestinian organisation, Hamas, for arms.
Broadcasters ITV, Channels 4 and Five are to show the appeal later.
Sky, whose news channel is widely available in the Middle East, is considering its decision.
The DEC, which represents more than a dozen aid agencies, is asking for money to buy food, medicine and blankets following the Israeli assault on Gaza.
Labour MP Richard Burden is putting forward the early day motion and he believed 57 MPs from different parties were supportive. "I think there's great concern about what the BBC has done here."
However, Culture Secretary Andy Burnham has said the BBC is right to make its own judgement over the appeal.
BBC director-general Mark Thompson said broadcasting the appeal risks undermining public confidence in the corporation's impartiality.
Mr Thompson said the danger for the BBC "is that this could be interpreted as taking a political stance on an ongoing story".
A string of politicians, including International Secretary Douglas Alexander, Communities Secretary Hazel Blears and opposition spokesmen, have urged the BBC to reconsider its position.
Their comments drew criticism from BBC Trust chairman Michael Lyons who said some were "coming close to constituting undue interference in the editorial independence of the BBC".
The corporation's former director-general, Greg Dyke, said it was in a "no-win" situation.