The two candidates were to meet Tuesday to work on specifics of an agreement, the Boston Herald reported.
"Elizabeth is committed to getting this done, and her campaign manager is ready to discuss a number of options at the meeting that Elizabeth thinks could be effective in preventing outside ads," Warren spokeswoman Alethea Harney said.
"If Scott Brown is really willing to accept Elizabeth's challenge, this can happen."
The Herald said its efforts to reach Brown were unsuccessful Monday but he told Politico he's "glad Professor Warren seems to be coming around on this issue."
The race, Brown said, "is going to be decided by the people of Massachusetts, not by the tens of millions of outside-interest dollars coming into our state."
Attack ads have targeted both candidates, with the League of Conservation Voters criticizing Brown, American Crossroads, Warren.
Millions of dollars from Massachusetts and outside the state have poured into the campaigns, as the Senate seat is viewed as critical to which party controls the Senate.
Warren, a professor at Harvard Law School, has a slim margin in recent polls, the Herald said.