Prime Minister Boyko Borisov has already demanded the resignations of Interior Ministry Chief Secretary Svetlozar Lazarov and counter-intelligence head Vladimir Pisanchev.

Borisov earlier explained he would take the step on a cabinet meeting Friday or Wednesday, after having insisted for weeks that neither Pisanchev nor Lazarov should be replaced.

His clash with ex-Interior Minister Veselin Vuchkov, who insisted on the reshuffles, led on Wednesday to the latter's resignation.

The Prime Minister was quick to interpret Vuchkov's move as "incorrect" and hinted it might have been inspired by the opposition, or as he put it: "colleagues from the [Bulgarian Socialist Party (BSP), the Movement for Rights and Freedoms (DPS) and Ataka"].

The first two parties formed in 2013-2014 the previous elected government, while nationalist Ataka was considered to be a "kingmaker" helping the socialist-liberal axis to cling to power.

"I told him [junior coalition partner Reformist Bloc's co-Chair Radan Kanev] that on Thursday I will come to Parliament, I will announce the resignations, I will demand the resignations of Pisanchev and Lazarov."

Kanev has been among the most fervent critics of the two top cadres. On Wednesday he said Vuchkov should be talked into staying in the government.

In Borisov's words, he is forced to take the step to fend off doubts that he is keeping the two on their posts "not for stability, but because he is dependent."

Borisov also proposed Deputy PM Rumyana Bachavarova as Vuchkov's most likely successor.

On Thursday Kanev, speaking for the Bulgarian National Radio, said that Bachvarova's candidacy is a "strong one."