>> As Beijing gets ready to choose new top leaders a potential candidate in the city of Chongqing has been put under the spotlight. State media making an abrupt announcement over the weekend saying Sun Zhengcai had been removed as party chief and replaced by an official close to president Xi Jinping.
Who's been on an anticorruption crusade since he took power. Reuters' Ben Blanchard explains why Sun is in the crosshairs.>> Sources have told Reuters, including sources who were briefed on the investigation, that he's currently undergoing investigation by the communist party for suspected serious breaches of discipline. Now this could be anything from bribery, to doubting key party policies, we just don't know at the moment.
It seems also at the moment that this investigation is in an initial stage and it's possible that they may not actually go ahead with a formal investigation.>> Chongqing is one of China's most important cities. Luring foreign brands with its tax breaks, cheap labor and land, it makes a third of the world's laptops.
It's also well known for its links to disgraced former party boss, Bo Xilai, who, himself was once a contender for top leadership before a dramatic corruption scandal in 2013 saw him jailed for life.>> Sun Zhengcai, or at least his government in Chongqing, had been criticized by the communist party in February for not doing enough to root out what they call the pernicious influence of Bo Xilai.
So sources have told us that because of this criticism, Sun's star really was on the wane. That he wasn't seen as being effective enough. He wasn't seen as enforcing communist party discipline and he wasn't seen as strong enough in getting rid of all the people who we suspect still support Bo Xilai in Chongqing.
>> Diplomatic sources say Sun was scheduled to visit Europe recently but that trip was cancelled. His last public appearance noted by state media last Wednesday, Beijing is yet to announce what's become of him.