State Rep. Paul Thissen, a Democrat, will officially announce his 2010 run for governor of Minnesota Thursday, his campaign committee revealed in a press release.

Paul Thissen

The event, at Thissen’s home in Minneapolis, will confirm a bid that already appeared certain, as the candidate formed an exploratory campaign committee in November.

A Harvard University graduate, Thissen boasts experience in both the private and public sectors as an attorney, four-term state legislator and current chairman of the state House Health and Human Services Committee.  

But he is joining a Democratic lineup that already contains declared candidates with higher profiles in statewide politics, including Mark Dayton , who represented Minnesota in the U.S. Senate from 2001 to 2007, and former state House Minority Leader Matt Entenza . And the field could grow crowded with others, as the parties prepare for a competitive contest to succeed retiring two-term Republican Gov. Tim Pawlenty .