Gingrich to end campaign

National media outlets are reporting that House Speaker Newt Gingrich will drop his bid for the Republican presidential nomination.

This from CBS News:

Newt Gingrich on Wednesday unofficially conceded the Republican presidential race to Mitt Romney, calling on conservatives to unite behind the presumptive nominee.

Following Romney's clean sweep of all five primaries on Tuesday - including Delaware, where Gingrich had staked the remainder of his tattered campaign - the former House speaker said in a speech to the Gaston County GOP here that "it's pretty clear Gov. Romney is gonna be the nominee."

You can read the rest of that story here.