(WGN-AM)- A crowded Democratic field for Cook County Board president got another entry today when the president of the agency that oversees wastewater treatment for the county kicked off his campaign.

Terrence J. O'Brien, Metropolitan Water Reclamation District board president, is seeking his party's nomination in the February primary.

"I want to do for Cook County Government, what I have done for the Metropolitan Water Reclamation District of Greater Chicago. So, I am officially announcing my candidacy for President of Cook County Board," O'Brien said in a statement sent to reporters. The Democratic field includes already includes incumbent Todd Stroger, Circuit Clerk Dorothy Brown and Ald. Toni Preckwinkle (4th).

Others mulling a run are U.S. Rep. Danny Davis (D-Ill.), Sheriff Tom Dart and Cook County Commissioner Larry Suffredin.

The field of potential candidates has grown in recent weeks since Commissioner Forrest Claypool (D-Chicago) said he was not going to seek the job of leading county government.

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