WASHINGTON (CNN) -- Maine's two senators -- among the more centrist Republicans in the Senate -- have endorsed Sen. John McCain's likely presidential bid, the Arizona Republican's presidential exploratory committee announced Monday.

Sens. Olympia Snowe and Susan Collins will serve as co-chairs of McCain's exploratory committee in Maine and Josh Tardy, the GOP leader in the state's House of Representatives, will server as vice chair.

Snowe said she has known McCain "for many years," and finds him to be "genuine, straightforward, and honest."

"He understands the issues facing our nation and has a proven track record of addressing the challenges we face," Snowe said in a statement.

Collins, who serves with McCain on the Senate Armed Services Committee, praised his foreign policy credentials and said, "I can think of no better person to lead our nation than John McCain."

Both Snowe and Collins have come out against President Bush's plan to increase troops in Iraq, a move McCain strongly supports.