Ukrainian President Viktor Yanukovych is not letting illness temper his criticism of the opposition and its non-stop anti-government protests.
Officials say Yanukovych has gone on sick leave for an acute respiratory infection and fever.
But that did not stop him from issuing a statement accusing opposition leaders of escalating the crisis. He said they are encouraging people to stand outside in freezing weather just to advance their political ambitions.
Yanukovych says the government has fulfilled its obligations to end the standoff. They include a conditional amnesty for arrested protesters and replacing his prime minister.
U.S. Secretary of State John Kerry telephoned opposition leaders Thursday. He commended them for what a spokeswoman calls speaking out against violence and their courageous defense of democracy.
Ukrainians took to the streets in November when President Yanukovych backed out of a trade deal with the European Union in favor of closer ties to Russia.
Russian President Vladimir Putin said Wednesday he wants to wait for a new government in Ukraine before proceeding with a promised $15 billion loan to Ukraine along with substantial natural gas discounts.
Earlier this week, the Standard and Poor's rating agency downgraded Ukraine's credit rating, in part because of what it calls the country's "distressed civil society" and "weakened political institutions," and its questionable ability to repay its debts.