Scott Brown's official announcement could come as early as next week, according to a report from WMUR.
Brown has moved to his family's summer home in Rye.
Brown has been campaigning across the Granite State in the past couple weeks, since announcing he was forming an exploratory committee during a Republican convention in Nashua.
Brown will face off against several Republican challengers in a primary.
Former U.S. Senator Bob Smith, former state Senator Jim Rubens, and Republican activist Karen Testerman are also running.
The winner of the primary will take on incumbent Democrat Jeanne Shaheen in November.
Shaheen has challenged Brown to take the "People's Pledge," which is meant to limit negative attack ads funded by third-party groups.
Brown has said he doesn't plan to sign the pledge, despite having done so during his failed bid for U.S. Senate in Massachusetts in 2012.