In Washington, the Obama administration, which has toughened its line toward Syria in recent weeks, officially welcomed Syrian democracy advocates based in the United States. Secretary of State Hillary Rodham Clinton met with them on Tuesday as more American lawmakers called for punitive steps against Mr. Assad and his officials, beyond the economic and travel sanctions already imposed.

The American antipathy for Mr. Assad was also on display at the confirmation hearing in Washington for Robert S. Ford, the American ambassador to Syria, who called the crackdown on protesters “brutal” and “outrageous.” Mr. Ford, who has been serving in Syria since January under a recess appointment by President Obama, told the Senate Foreign Relations Committee that the behavior of Mr. Assad’s government "has been atrocious" and that Syrians were already planning for the day when he is longer president.

At the United Nations, news of the escalating violence appeared to have broken a deadlock over Syria that had lasted since May. Diplomats spent Tuesday attempting to sort out exactly what form a condemnation might take.

Besides Russia, other nations that had opposed action against Syria, including Brazil, India and South Africa, decided that the council now had to do something. While sanctions were not part of the negotiations, there was broad consensus on Tuesday that the council should both condemn the violence against civilians and demand that it stop, and should call for concrete steps toward an inclusive political process, diplomats said.

Most of the proposals were included in a draft resolution that the European members of the council — Britain, Germany, France and Portugal — submitted in May and resurrected on Monday. Brazil came forward with its own proposal on Tuesday that contained many of the same elements, so a compromise was being negotiated.

One key issue was whether the council would equate any attacks by the Assad regime on the civilian population with scattered violence carried out by protesters.

Before Tuesday, Russia had rejected calls for a resolution, saying the uprising in Syria was an internal matter and warning that a resolution might, as in Libya, be used as a justification for military action.