Russian Foreign Minister Sergei Lavrov met Tuesday in Moscow with Ahmad Jarba, leader of the Western-backed Syrian National Coalition, to discuss next week's talks in Geneva, Switzerland.
Russian news agency RIA Novosti reported Lavrov received assurances from Jarba that his party would attend Feb. 10 negotiations, part of the second round of talks aimed at finding a political solution to the Syrian crisis.
Barroso said during his meeting Tuesday with U.N. General Assembly President John Ashe next week's talks offered an opportunity to advance confidence-building measures from both sides.
"Geneva II is the only vehicle left to engage the opposition and the regime on the political transition," he said in a statement.
Negotiators behind Geneva II said it will serve as a venue to pave the way toward a transitional government that would run the country until elections can be held.
Prospects for the talks were clouded by reservations over the role for Syrian President Bashar Assad
Assad has insisted he would not step down or share power with the opposition.
Negotiations in Geneva began earlier this week. The United Nations said Syrian rebel groups have agreed to attend the Feb. 10 session, but the government hasn't committed.