The Boston Globe is reporting that Massachusetts state Treasurer Timothy Cahill will announce an independent run for governor on Wednesday, shaking up an already charged 2010 governor’s race.

Cahill, who changed his registration from Democrat to unenrolled in June, would be an instant contender in a three-man race. A Boston Globe poll of Massachusetts adults conducted in July shows him in a dead heat with Gov. Deval Patrick, the embattled Democratic incumbent, in such a hypothetical match-up, with the prospective Republican nominee, either health care executive Charlie Baker or businessman Christy Mihos coming in about 10 percentage points back.

In contrast, a Rasmussen Reports poll of a two-man race, conducted in August, showed Mihos leading Patrick while Baker and Patrick were essentially tied.