AUGUSTA — A special Maine legislative panel is poised to begin its investigation into a disputed state Senate seat.

The committee, which has been tasked with determining a winner in the District 25 race, will begin its work on Tuesday.

The Republican-led Maine Senate voted to provisionally seat Republican Cathy Manchester on Wednesday, even though Democratic Secretary of State Matthew Dunlap had said that Democrat Cathy Breen should be seated.

Unofficial results had shown Breen winning, but the recount flipped the results in Manchester’s favor.

Democrats say they’re concerned about possible ballot tampering because 21 ballots for Manchester found during the recount were unaccounted for on Election Day.

The panel plans to call witnesses to testify and examine the disputed ballots. Once they determine a winner, the full Senate will vote.