KIEV, Ukraine -- Ukraine's parliament approved a constitutional amendment Tuesday to allow deputies to defect from their parties and join a new coalition forming around Kremlin-friendly President Viktor Yanukovych's party.
The amendment will drastically ease Mr. Yanukovych's ability to consolidate power, as it allows his party to lure deputies away from the camps of his rivals, including the bloc of former Prime Minister Yulia Tymoshenko.
The current constitution only allows parliamentary factions to join a coalition, not individual deputies. The rule has helped enforce party discipline even as alliances began to shift in Mr. Yanukovych's favor after he was elected last month.
Mr. Yanukovych's rivals lashed out against Tuesday's vote, with a member of former President Viktor Yushchenko's party calling it a"constitutional coup" and vowing to challenge it in court.
Ms. Tymoshenko, who lost the presidential election to Mr. Yanukovych by a narrow margin, meanwhile tried to rally opposition against him.
"I ask you, from now on, to give a commitment to one another to strongly oppose everything anti-Ukrainian," she said, addressing her supporters.
Signs of mutiny within her party emerged last week when seven of its members supported the no-confidence vote that ousted Ms. Tymoshenko from the powerful post of prime minister.
Yuriy Yakimenko, a political analyst at the Razumkov Center, said that if Yanukovych signs the amendment into law, it will be far easier for him to form a broad coalition capable of choosing one of his allies to become the new prime minister.