Senator John Kerry, US President Obama's nominee for Secretary of State, has said that the war in Syria is getting worse every day.
Mr Kerry was addressing the Senate Foreign Relations Committee, which must decide whether or not to confirm him in the post.
Mr Kerry said it was important for Republicans and Democrats to come together to agree on how best to deal with the crisis in Syria.
Mr Kerry was asked about his outreach to President Bashar al-Assad, now an international pariah after months of civil war and unending violence against his citizens.
The senator said there was a moment where Syria reached out to the West but that the moment has long passed.
Senator John McCain, a leading Republican and a fierce critic of Mr Obama's policy on Syria, said the status quo is unacceptable with the United Nations estimating that 60,000 have been killed and the heavy influx of refugees in Jordan and Turkey.
After a recent visit to the refugee camps, Mr McCain warned that Syrians frustrated with the US response will be a recruitment target for extremists.
Mr Kerry said it was imperative to continue discussions with Russia and others in dealing with Syria but that "I don't have optimism".
Elsewhere, the Syrian army has stepped up its attack on opposition Sunni Muslim strongholds in the central city of Homs, bringing in ground forces to try to secure passage for its forces through a major road junction.
Around 15,000 Sunni civilians were trapped on the southern and western edge of the city today an artery crucial to let Assad's forces travel between Damascus and the Mediterranean coast, opposition campaigners in Homs said.
They said army rocket, artillery and aerial bombardment had killed at last 120 civilians and 30 opposition fighters since Sunday.
Syrian authorities have banned most independent media, making it difficult to verify such reports on the ground.
The sources also said shabbiha militiamen loyal to President Bashar al-Assad had killed more than 100 Sunni men, women and children when they overran a nearby area 10 days ago.
Activist Nader al-Husseini, speaking by phone from the western sector of Homs, said at least 10,000 shabbiha had been brought from the coastal city of Tartous to back up the regular army.