Bulgaria's MPs are about to start on Thursday a new procedure to elect and appoint a constitutional judge from the parliamentary quota after the nominee was blocked by the president in an unprecedented show of protest.

A seat in the Constitutional Court remained empty when last Thursday Bulgarian President Rosen Plevneliev walked out just as controversial judge Veneta Markovska was about to swear in.

Markovska's name had become implicated in allegations of trade in influence, which she was unable to dispel, but nevertheless chose not to resign, after being elected to the Constitutional Court by Parliament.

Markovska's appointment stirred a huge scandal in Bulgaria over a tipoff sent to Members of the Parliament from the opposition and an investigative journalistic report raising suspicions of trading influence and corruption. She was approved by the MPs without a hearing and explanations about the allegations.

The case "Markovska" "traveled" all the way to the European Commission, which warned Bulgaria twice about the possibility of issuing an interim report under the Cooperation and Verification Mechanism.

At the beginning of this week Bulgaria's Prime Minister Boyko Borisov unexpectedly informally invited UDF to nominate a replacement for Markovska on grounds the formation was the oldest right-wing party in Bulgaria and is a member of the European People's Party, EPP, similarly to his ruling Citizens for European Development of Bulgaria party, GERB.

The move is interpreted as an attempt from the PM to attract the allegiance of the Union and create further divisions in the feeble Blue Coalition between the UDF and Democrats for Strong Bulgaria, DSB.

Former Bulgarian President, Petar Stoyanov, who was nominated for constitutional judge by right-wing Union of Democratic Forces, is expected however to be boycotted by all opposition parties in parliament, including his own.

On Tuesday, shortly after UDF Chair, Emil Kabaivanov presented Stoyanov's nomination, it emerged that the former president can count on the support of the MPs from the ruling GERB party only.

The Socialist party and the ethnic Turks, as well as the die-hard right-wingers from Democrats for Strong Bulgaria, DSB said they will boycott the new procedure since, they claim, it has been rigged.

Stoyanov asked to have three days to say if he would accept the nomination and is likely to turn it down, according to media reports.