He has been leader for 15 years, apart from 20 months when he was toppled from power during 1994-95.
The Midlands Labour Party is investigating complaints and counter-allegations over the conduct of selection meetings.
Mr Soulsby and the Labour group's deputy leader, chair, secretary, chief whip and another whip have made a series of complaints against leading Leicester Labour Party members. Among the allegations is that selections have been influenced by entryism by taxi drivers and their families, seeking to introduce more favourable taxi licensing laws.
A Midlands Labour Party spokesman said: 'We have received a number of letters and we are considering the contents at the moment.' He confirmed the selection process had been suspended in two key wards.
Mr Soulsby was unavailable for comment.