Turkish Parliament convene for a debate in Ankara Jan. 20, 2015. Parliament was to vote on Tuesday on whether to commit four former ministers for trial over the corruption allegations.

The Turkish parliament voted on Wednesday not to send to trial four former ministers accused of wrongdoing in a corruption investigation, in a boost to President Tayyip Erdogan who cast the graft scandal as a plot to undermine his rule.

The outcome was expected as the ruling AK Party (AKP) has a large majority in parliament and it closes one of the last avenues in the investigation after earlier court cases had already been dropped.

The four separate votes on the ex-ministers indicated some 40 AKP deputies voted to commit them to trial, in a blow to party unity on the issue. The opposition fell several dozen short of the 276 votes needed for the motions to be carried.

The investigation became public in December 2013 and posed one of the biggest challenges to Erdogan and his decade-long rule. He cast the probe as a coup attempt orchestrated by his former ally, U.S.-based cleric Fethullah Gulen.

The affair led to the resignation of the economy, interior and urbanisation ministers and European Union Affairs Minister Egemen Bagis lost his post in a subsequent reshuffle. All four denied wrongdoing.

Erdogan fought back by purging the state apparatus, reassigning thousands of police and hundreds of judges and prosecutors deemed loyal to Gulen, in what was seen as a cleansing of the cleric’s influence in the state.

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