Ukraine's opposition says embattled President Viktor Yanukovych has left the capital, and called for early presidential elections.
Opposition leader Vitaly Klitschko on Saturday called on President Yanukovych to resign so that new elections can be held no later than May.
Elsewhere, parliament has elected a new speaker who is a longtime ally of jailed opposition leader Yulia Tymoshenko.
Oleksandr Turchynov was elected speaker Saturday, a day after lawmakers voted to amend a law that could result in Tymoshenko's release.
The new parliament speaker was elected shortly after pro-government speaker Volodymyr Rybak submitted his resignation Saturday, citing ill health.
Thousands of protesters remained in Kyiv's Independence Square, objecting to a deal signed Friday by Ukraine's president and the opposition aimed at ending the country's political crisis.
Many protesters continue to demand the immediate resignation of President Yanukovych.
The United States says the deal is "very, very fragile" and needs global support. A State Department official said the agreement will be a "tough sell" to the opposition in the streets because of the recent violence and deaths.
U.S. President Barack Obama telephoned Russian President Vladimir Putin Friday to talk about Ukraine. A White House official said both leaders agree on the need to quickly implement the deal and encourage all sides to avoid violence.
Friday's agreement returns Ukraine to its 2004 constitution, limiting presidential powers. The deal also includes setting up a coalition government and early elections.
Protests erupted in Ukraine in November when President Yanukovych backed out of a trade deal with the European Union in favor of closer ties to Russia.
The protests began peacefully but sank into violence earlier this month, leaving nearly 100 people dead, including some protesters shot in the head by police snipers.
A U.N. spokesperson says Secretary-General Ban Ki-moon phoned Ukrainian President Yanukovych to personally welcome Friday's agreement. The official says Mr. Ban commends the spirit of compromise.
Foreign ministers from France, Germany and Poland helped broker the deal.
Along with early elections, the agreement would replace Interior Minister Vitali Zakharchenko, who the opposition blames for the deaths of protesters. It amends the criminal code to allow the release of former prime minister Yulia Tymoshenko from prison.
Ukraine is split between those in the east who favor ties with Russia, and those in the west who lean towards the European Union.
President Obama is downplaying suggestions that Ukraine is a battlefield in a new Cold War with Russia. He said this week that the U.S. wants to make sure the people of Ukraine are able to make their own decision about the future.
A State Department official says the U.S., Europe, Russia and Ukraine all have shared interests.