Mayer Brown Rowe & Maw (MBR&M) will start the task of picking a new chairman on 1 June, but debate still centres on whether the firm should have one full-time chairman or two co-chairmen, who would continue fee-earning duties.
It is understood that the process could last as long as five months. Five candidates are said to have thrown their hats into the ring for the job, including UK managing partner Paul Maher.
Other names are said to include managing partner of Washington DC Kenneth Geller, Chicago's litigation heavyweight James Holzauer, pensions partner Herbert Krueger and corporate rainmaker Frederick Thomas. All candidates are members of the firm's management committee, known internally as the policy and planning committee.
Partners decided to start the process of choosing a new chairman at their recent partners' meeting in Chicago. At that time a management sub-committee was formed, which will be responsible for sounding out partners' opinions on their favoured candidate. The final vote is taken by the 12-partner policy and planning committee.
Current managing partner Ty Fahner is due to step down next June, giving the successor a six to seven-month handover period.
MBR&M generated fee income of $980m (£560m) in 2005, of which London accounted for $145m (£82.86m).