Ukraine’s President Petro Poroshenko says he is willing to hold a referendum leading to a more decentralised state.
But it is not clear whether that would satisfy the pro-Russian rebels in the east, who do not recognise Kiev’s rule.
The Minsk ceasefire accord reached in February called for adoption of a new constitution by the end of 2015, including decentralisation of power.
Mr Poroshenko raised the issue of a referendum at his first meeting with a new constitutional reform committee.
“I’m ready to launch a referendum on the issue of state governance if you decide it is necessary,” he said.
He said opinion polls indicated that nearly 90% of Ukrainians would vote to keep the “unitary state” model, rather than opt for a federal state.
Russia has long argued that Ukraine should become a federation, and the Moscow-backed separatists in eastern Ukraine have declared their own “people’s republics” in Donetsk and Luhansk.
“Decentralisation has nothing to do with federalisation,” Mr Poroshenko told the new committee on Monday. “Ukraine was, is and I’m convinced will remain a unitary state.”