The move means that Kuchma cannot dismiss Yanukovich from the post of prime minister, as demanded by the opposition, until he returns from leave.
Parliamentary speaker Volodymyr Lytvyn said the legislature's consultations on passing both electoral charges and constitutional reforms would continue tomorrow.
He said outgoing President Kuchma was ready to attend the session and sign them into law immediately after the vote.
Supporters of opposition candidate Viktor Yushchenko say the changes are necessary to close loopholes for fraud.
Evidence of vote-rigging prompted the Supreme Court to cancel the 21 November victory of the Kremlin-backed Yanukovych and order the repeat vote.
But communists, socialists, and pro-government factions said they would only pass the electoral changes simultaneously with a constitutional reform that would trim presidential powers.
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