Ukraine’s opposition is seeking a parliamentary vote on curbing the powers of President Viktor Yanukovych as a step toward resolving the country’s political crisis.

The opposition is forcing the issue with building international support behind it. The European Union and the U.S. are discussing potential aid if Ukraine forms a new government, U.S. State Department spokeswoman Jen Psaki said in Washington yesterday. By returning to the country’s 2004 constitution, which shifts authority from the president to parliament, the opposition may be more willing to take a share of power, UDAR party leader Vitali Klitschko said.

Ukraine has been rattled by the biggest anti-government protests since gaining independence in 1991, with seven demonstrators killed in clashes last month. While violence receded after parliament repealed anti-protest laws and the prime minister resigned last week, street rallies continued and the opposition has refused to take cabinet posts.

“Everybody now knows just how dangerous it is to concentrate power in just a few hands,” Klitschko, a former heavyweight boxing champion, said in parliament yesterday. “When parties and lawmakers will indeed become the decision- makers, then we can talk about forming a government that will have parliament’s trust and support.”

Prospects of Western aid helped boost Ukraine’s bonds yesterday, with the yield on dollar-denominated notes due in June dropping 115 basis points, or 1.15 percentage point, to 13.54 percent, according to data compiled by Bloomberg.

Parliament starts its session at 10 a.m. in Kiev and it’s unclear if or when a vote on constitutional change will be held. Yanukovych’s party, which controls the legislature, tried to block it from getting on the agenda.

“The next step is the creation of a new government, and then we will consider what support we would be able to and be prepared to provide,” Psaki said. The EU is discussing “if we can do something more in this particular phase,” European Commission President Jose Barroso said in Brussels yesterday.

Ukraine needs “real financial help” to end its crisis, Arseniy Yatsenyuk, the head of the opposition Batkivshchyna party, said in a statement.

Barroso said EU’s main offer for Ukraine continues to be the association agreement that Yanukovych refused to sign in November, which would open the bloc to Ukraine’s exports.

Russia in December agreed to lend Ukraine $15 billion and to reduce the price for natural gas deliveries after Yanukovych rejected an EU pact. After buying $3 billion of Ukrainian bonds in December, further aid may be on hold until a new cabinet is formed, President Vladimir Putin said Jan. 29.

Under pressure from Western diplomats, Ukraine allowed an activist, who was abducted and tortured, to leave to Lithuania to get medical treatment, Rasa Jakilaitiene, spokeswoman for Lithuania’s foreign ministry, said by phone yesterday.

“Although they almost destroyed me physically, they didn’t break my spirit,” Dmitri Bulatov said in a statement from the Vilnius University Hospital, where he is being treated. “I’ll continue the battle that’s begun, I’ll continue forward and seek democracy in Ukraine. I won’t withdraw.”