The Brown campaign said in a press release that it would agree to allow former NBC ­anchor Tom Brokaw to moderate.

Elizabeth Warren has already accepted the Sept. 27 debate, but Brown had previously not committed. The candidates are jointly committed to two other televised debates so far, one in the Boston market and a second one in Western Massachusetts.

Vicki Kennedy, Senator Kennedy’s widow, had proposed a third debate. But she has been an active Democrat, causing some to question whether Brown should accept the invitation. And MSNBC, home to many liberal talk show hosts, had been mentioned as a potential broadcast partner.