Rep. Rush Holt (D-N.J.), an underdog U.S. Senate contender in New Jersey, has tapped journalist Glenn Greenwald for an online town hall meeting he is hosting Tuesday, his campaign announced Monday.

Greenwald, a columnist and blogger for London's Guardian newspaper, was first to report the National Security Agency's sweeping telephone surveillance effort in June. He expressed his support for Holt and -- dinged his leading opponent -- in a tweet earlier this month.