The man approached the Gingriches during the signing at a downtown Minneapolis hotel, dumped a cracker box full of colorful confetti on the pair and said, "Feel the rainbow, Newt! Stop the hate! Stop anti-gay politics!"
Two Associated Press reporters witnessed the event. The man was quickly pushed out of the room by an event organizer as the Gingriches brushed confetti out of their hair and laps.
Newt Gingrich smiled as he brushed confetti off the table, and said, "Nice to live in a free country."
Although authorities couldn't immediately confirm the man's identity, he appeared to be Nick Espinosa, a prankster who has disrupted at least two other political events in Minnesota, including one in which he dumped a bagful of pennies in the lap of a Republican candidate for governor last year. In that prank, Espinosa - who has also used the name Robert Erickson - told reporters he was trying to highlight immigration issues.
Espinosa emailed reporters later Tuesday and attached pictures of the confetti attack. He said it was a protest against a proposal to amend Minnesota's Constitution to ban gay marriage.
Newt Gingrich was due to give a speech at the event sponsored by the Minnesota Family Council later in the evening.