UN and Arab League envoy Kofi Annan has left Syria without reaching a deal with embattled president Bashar al-Assad as regime forces assaulted the northern city of Idlib, a stronghold of opposition units.
Annan is still confident Assad can be persuaded to accept a peace deal to stop the killing, allow humanitarian corridors in Homs and start a constructive political dialogue with the opposition.
Diplomatic efforts are also focused on Russia, which in January vetoed a US-backed resolution to urge Syria to stop the siege in Homs and is considered one of Assad's staunchest supporters.
A former Secretary General of the UN, Annan has left Syria empty-handed but his initiative, he says, "will have a real impact on the ground".
"Once it's agreed, it will help launch the process and help end the crisis on the ground," he told reporters at the end of his two-day visit to Syria. "It's going to be difficult but we have to have hope."
Assad refused to accept any political solution while "terrorist groups" were still in the field. Opposition leaders denied dialogue talks while the government continued its brutal crackdown on civilians.
Last week, Russia claimed that forces loyal to Assad are battling al-Qaida-backed terrorists, including at least 15,000 foreign fighters.
Russia's deputy ambassador, Mikhail Lebedev, said government troops were protecting Syrian infrastructure, including schools and hospitals, from large-scale attacks by rebel forces backed by al-Qaida.
But Annan hopes Russia will back a plan that, according to the International Crisis Group, comprises an early transfer of power while preserving the integrity of key state institutions, ensures an overhaul of security services and "puts in place a process of transitional justice and national reconciliation that reassures Syrian constituencies alarmed by the dual prospect of tumultuous change and violent score-settling".
After his visit to Syria, Annan is heading for Qatar.