Two parties in Ukraine's governing coalition say that they won't abandon the grouping amid intense disputes over a proposal to give more power to Ukraine's regions, including the rebel-held east.

However, the two parties' opposition to the measure appears firm and President Petro Poroshenko faces a steep battle to push it through.

Oleg Berezyuk, head of the Samopomich faction, said Wednesday it will "remain in the coalition in the role of opposition within the parliamentary majority." A member of Poroshenko's faction, Igor Kononeko, said the faction of former Prime Minister Yulia Tymoshenko would also remain in the coalition, the Interfax news agency reported.

Three national guard members died after a grenade was thrown from a crowd of protesters outside parliament on Monday as lawmakers gave preliminary approval to the measure.