Rep. Michael H. Michaud, D-Maine, formally announced Thursday that he is running for governor in the Pine Tree State, creating a competitive and crowded race for the 2nd District he leaves behind.

Michaud had been exploring a gubernatorial bid since June.

Three Democrats and one Republican have already entered the race for his House seat, which operatives say will likely be competitive now that it’s an open-seat race.

Democratic state Sen. Emily Cain, who will likely receive the support of EMILY’s List, was the first to announce her bid to replace Michaud. She was followed by two more Democrats, state Sen. Troy Jackson and Naval Officer Alden Smith.

On the Republican side, Assistant House Minority Leader Alex Willette was the first to announce he is seeking the seat.

Other Republicans said to be considering the race include former House Minority Leader Josh Tardy, former state Treasure Bruce Poliquin and former state Sen. Kevin Raye, who has lost to Michaud twice: in 2002 by 4 points and again in 2012 by nearly 17 points.

President Barack Obama carried the 2nd District by a 9-point margin in 2012.

The 2nd District is rated a Democrat Favored contest by Rothenberg Political Report/Roll Call.