Ukraine's President Viktor Yanukovych returned to work Monday after four days of sick leave, as opposition leaders said they would seek changes to the country's constitution that would limit presidential powers.
The opposition wants to restore constitutional changes limiting the powers of the president and giving parliament more say in forming governments. Those changes were enacted in 2004 but later overturned by the country's constitutional court.
Opposition leader Arseniy Yatsenyuk said Monday that restoring the 2004 constitution would "cancel the dictatorial powers of the president."
Ukraine's parliament is expected to discuss that proposal on Tuesday, as well as the opposition's demand that those arrested during anti-government protests be granted amnesty unconditionally.
The opposition has also demanded that Yanukovych resign and new presidential elections be held.
About 30,000 anti-government demonstrators seeking his ouster protested Sunday in Kyiv's barricaded Independence Square. It was one of the largest gatherings in two months of demonstrations against the Yanukovych government.
The United States has supported the protest movement, with Secretary of State John Kerry saying it represents the former Soviet republic's fight for "a democratic, European future."
The protests started in November when Yanukovych, under pressure from Moscow, turned down a partnership with the European Union. The Ukraine faces severe economic troubles and Russia has promised a $15-billion rescue.