BUCHAREST (Reuters) - Thousands of Romanians protested on Thursday against the Senate’s decision to shut down a potential manslaughter investigation into a former deputy prime minister over the death of a police motorcycle outrider.

Gabriel Oprea, a member of the Senate, was traveling in a motorcade to which he was not entitled in late 2015 when Bogdan Gigina, one of his police escorts, crashed when his bike hit a pothole in rainy conditions.

Anti-corruption prosecutors had asked senators to approve an inquiry into whether Oprea, by using the motorcade, was responsible for the accident. Under Romanian law, senators can only be investigated with lawmakers’ approval.

Oprea, who denies the charges, told senators on Monday that he could not have been responsible for the death from the back seat of the car and asked them to vote against. A majority did, drawing criticism from President Klaus Iohannis and foreign diplomats.

“It is a political vote that is blocking justice,” chief anti-corruption prosecutor Laura Codruta Kovesi told reporters. “A mother is left waiting.”

Lawmakers have rejected several similar requests in recent years with no clear legal reason. The European Commission, which keeps Romania’s justice system under special monitoring, has repeatedly criticized parliament for this in its annual reports.

Some 2,000 people protested outside parliament in Bucharest, carrying banners that said “Solidarity with the Gigina family” and “Nobody is above the law”. They shouted: “We want justice, not immunity” and “Shame on you.”

Protesters also gathered in the cities of Cluj, Iasi, Galati and Timisoara, state news agency Agerpres reported.

Earlier on Thursday, Oprea said on Facebook that he may have been wrong to ask his colleagues to reject the investigation and that he would request the vote be repeated.

“I know I am innocent and I am not running from justice,” he said.

“I also know that this case raises too many question marks. If you were me ... would you accept being told you killed a man even though you had absolutely no connection with any of the accident’s causes?”

It was unclear whether the vote could be repeated.

Prosecutors have launched several high-profile investigations in recent years - against ministers, lawmakers, mayors, magistrates and businessmen - in a crackdown that has exposed widespread graft.