Ukrainian President Petro Poroshenko suggested on Tuesday that Prime Minister Arseny Yatseniuk resign because his government had lost public support, but said there should not be a snap election.
The faction leader of Poroshenko's party said it would ask parliament to hold a no-confidence vote within hours.
Poroshenko called for General Prosecutor Viktor Shokin to resign and said: "The same parameters should be applied to the government also ... society has clearly decided that there have been more mistakes than achievements, and denied ministers its trust."
Speaking in parliament after the statement, Yatseniuk was not explicit about whether he would resign or not, saying he would accept whatever decision parliament made. Shokin did tender his resignation, however, the newspaper Ukrainska Pravda reported.
Poroshenko heads Ukraine's largest party, and Yatseniuk the next largest. Both are in the ruling coalition.
Maksym Burbak, the parliamentary leader of Yatseniuk's party, told lawmakers that the consequences of voting against the government would be felt "literally the next day - since this could trigger early elections and chaos".
If the government collapsed, it would dismay Ukraine's international backers, who have invested much cash and political capital supporting the government in its standoff with Moscow after Russia's annexation of Crimea in 2014.
Ukraine's failure to tackle corruption and implement reforms has already derailed a Western aid programme that keeps its war-ravaged economy afloat.
Last year, the International Monetary Fund gave Ukraine a $17.5 billion package to be spread over four years, but so far only $6.7 billion has been disbursed.
Ukraine has been waiting since October for the next tranche of aid, worth $1.7 billion, which has been held up by concerns over the slow pace of reform.
The economy minister quit at the start of February, complaining that corrupt vested interests were meddling in his ministry's work.
Ukraine's hryvnia currency weakened to a new 11-month low of more than 27 to the dollar on Tuesday, central bank data showed, and has fallen 12.2 percent since the start of this year alone.
The government is struggling to haul Ukraine out of recession at the same time as fighting a pro-Russian separatist insurgency in its industrial east.
Yatseniuk took office in 2014. His approval ratings have plunged to below 1 percent but he has no obvious successor, although the parliamentary speaker and the technocrat finance minister are considered contenders.