Candidates running for the open U.S. Senate seat in Massachusetts are split in their opinions about how nonprofit organizations should be regulated, the amount of money they should be allowed to spend on lobbying and a number of other key questions that could shape the sector in the coming years.

The candidates responded to a nine-questions survey distributed by the Massachusetts Nonprofit Network, which covered a wide swath of issues. All of the Democratic candidates returned the survey; so, too, did Republican Jack E. Robinson. Only state Sen. Scott Brown, a Republican candidate, did not respond.