BEIRUT - Syria's opposition coalition gave qualified backing Monday to its leader's surprise offer last week for a dialogue with President Bashar Assad to end the civil war, pressing him to respond definitively and even offering the added inducement that he could avoid trial if he resigned and left the country.

Although the offer made by the opposition leader, Mouaz al-Khatib, was by his own admission a personal gambit and was initially greeted with a torrent of criticism inside the Syrian opposition movement, his colleagues in the National Coalition of Syrian Revolutionary and Opposition Forces basically endorsed it over the weekend. While some complained that Al-Khatib had not consulted them before making the offer and a few even called for his resignation, others went along in part to counter the appearance of fractiousness that has long been a weakness in the opposition.

Al-Khatib, a respected Sunni cleric in exile who once was the head imam at the historic Umayyad Mosque in Damascus, said he would engage in dialogue with Assad's government only if it released 160,000 political prisoners and renewed all expired passports held by members of the Syrian diaspora, which includes large numbers of dissidents.

On Sunday, an aide to Assad gave a vague response. The aide, Ali Haidar, Syria's minister of national reconciliation, said in an interview with Russia Today, a Kremlin-financed news organization sympathetic to Syria's government, that the government was open to talks with any opposition members who reject violence. He also said it was willing to address the passport issue but not necessarily the release of prisoners. Haidar said the 160,000 figure was exaggerated and asked Al-Khatib to send a list of prisoner names.

While the opposition is still saying Assad's departure must be part of any political settlement to end the conflict, it is no longer a precondition for talks.

Apparently emboldened by the belated support from other members of the opposition coalition, as well as endorsements of his initiative from the U.N. secretary-general and special Syria envoy, Al-Khatib demanded during an interview with Al Jazeera on Monday that Assad give him "a clear stand" on the proposal.

"We say we will extend our hand for the interest of people and to help the regime leave peacefully," Al-Khatib said in the interview. "It is now in the hands of the regime."