Romanian Prime Minister Sorin Grindeanu has refused to quit office after his ruling Social Democratic Party (PSD) withdrew support and asked him to step down, potentially opening the way for prolonged political instability.

“I will not resign,” Grindeanu said late on Wednesday. “I have an obligation to act responsibly towards this country and towards my own party. I will step back only if President Klaus Iohannis will nominate a PSD member for my post after consulting with all political parties.”

PSD Chairman Liviu Dragnea told journalists after a meeting of the party’s executive committee that “all PSD cabinet members have handed in their resignations and the party is ready to continue governing the country after the PM announced he would step aside under certain conditions”.

“Since all cabinet members are resigning, we cannot talk about a government any more,” Dragnea added.

The PSD wound up a week-long performance review of Grindeanu’s six-month old cabinet on Wednesday evening and found it had failed to uphold an ambitious governing programme, which won the party an election victory in December and a comfortable parliament majority.

Grindeanu refuted the accusations, saying he missed implementing only nine measures out of 97 scheduled to be fulfilled over the first five months in office.

At the PSD meeting, the government performance analysis was presented by a former minister of finance currently on trial for taking bribes and hiding the money in a graveyard, according to prosecutors.

The junior partner of the PSD, the Alliance of Liberals and Democrats (ALDE), also said it will pull its backing for Grindeanu.

“We have voted to cancel our political support for prime minister Grindeanu. Our four cabinet members have already written their resignations,” ALDE Chairman Calin Popescu-Tariceanu said.

“We are well aware that there is a big difference between public perception of the government’s performance, which is rather positive, and reality, which is rather grim… A government without political backing cannot go on,” Tariceanu added.

Earlier on Wednesday, Grindeanu told journalists he did not intend to resign, but said he was expecting a “public execution”.

Over the last two weeks, Grindeanu has been targeted by fierce attacks from his own party, signalling a fallout with Dragnea. Several PSD leaders earlier suggested the prime minister should step aside.

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The ruling coalition can launch a vote of no confidence in parliament to remove him from office.

Dragnea wanted to become prime minister himself, but was denied the position because of a prior criminal conviction for voter fraud.

He was also put on trial by anti-corruption prosecutors on charges of official misconduct – the same crime that would have been decriminalised under a government proposal had Romanians not taken to the streets by the hundreds of thousands last year.