After months of speculation, the former Massachusetts senator moved to New Hampshire in December, created an exploratory committee last month and spent the last few weeks traveling around the state meeting voters. He plans to formally announce his campaign Thursday night in Portsmouth.
Brown won a special election in Massachusetts in 2010 and then lost his seat to Democrat Elizabeth Warren in 2012.
Hoping for a chance to unseat Democrat Jeanne Shaheen this fall, Brown faces former U.S. Sen. Bob Smith, former state Sen. Jim Rubens and conservative activist Karen Testerman in the GOP primary.
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