Number 10 denied press reports that David Cameron has abandoned hope of winning parliamentary approval to extend RAF operations against the Islamic State terror group - also known as ISIS, ISIL and Daesh - from Iraq into Syria.
But the prospect of a vote - once expected soon after the Commons returned from its summer break - now appears to be receding, with military action opposed not only by Labour leader Jeremy Corbyn but also by a group of 20-30 Conservatives who are resisting Mr Cameron's efforts to win them over.
British aircraft are already bombing Islamic State sites.
The Christian charity Embrace the Middle East told Premier that it too was against air strikes.
Jeremy Moodey, Chief Executive, said: "We do need to know exactly what we want to achieve and the key thing that we need is diplomatic talks.
"We need to be able to get everyone in a room together and be able to resolve this terrible, terrible civil war."
The PM's plans were dealt a further blow by a report from an influential Commons committee, which cautioned that he should not ask MPs to back action in the Middle Eastern state until he can show there is a clear plan both to defeat the jihadists and to end the bloody civil war.
The strongly worded report by the Foreign Affairs Select Committee warned that RAF strikes would only have a "marginal effect", but could be a "distraction" and compromise efforts to find a diplomatic solution to the crisis. The Tory-led cross-party committee said it was "not yet persuaded" that Mr Cameron would be able to address their concerns.
Mr Moodey also told the News Hour he was unsure air strikes would have any legal basis.
"We are able to intervene in another country in three circumstances, if we're invited in, if there's a UN resolution or if we're acting in self-defence," he said.
"We haven't been invited into Syria by the Assad regime, there is no UN resolution and i think it is stretching the point that bombing ISIS [Islamic State] is self-defence."
Mr Cameron was bruised by a 2013 Commons defeat on military action against the forces of Syrian dictator Bashar Assad, and his official spokeswoman said the PM would only go back to MPs if he was sure of "support across the House".
The spokeswoman told a Westminster briefing: "The position has not changed. If you look at what the Prime Minister was saying last month on this, you can't put a timescale on the vote because that comes down to going back to the House when there is greater consensus across the House of Commons for that action.
"The PM is clear that there is a case for doing more and he will keep working, and the UK Government will keep working with allies to look at what we can do to protect ourselves and others from the threat of ISIS. It is clearly for MPs that don't share those views to reflect on the threat from ISIL and what we do to protect ourselves from it."