Former House Speaker Newt Gingrich released the delegates he collected in his unsuccessful bid for the GOP presidential nomination, less than a week before the start of the Republican National Convention in Tampa.

Gingrich, who early on in the intraparty contest had vowed to fight for the nomination all the way to the convention, said in an open letter to delegates Tuesday that it was "now time for all Republicans to come together in common purpose to defeat President Barack Obama and Vice President Joe Biden."