As we type, Mitt Romney is giving a live speech to the Conservative Political Action Conference in Washington. GOP sources say that, during this rally, he will announce the suspension of his campaign. According to Time.com, he will say the following: "If I fight on in my campaign, all the way to the convention, I would forestall the launch of a national campaign and make it more likely that Senator Clinton or [Barack] Obama would win."

Romney to Quit Race [Time]

Update: Snippets from his speech just now, in which he said he was stepping aside so that McCain could begin a national campaign:

"Today, we are a nation at war. And Barack and Hillary have made their intentions clear regarding Iraq and the war on terror. They would retreat and declare defeat. The consequences of that would be devastating.… Frankly, in this time of war I simply cannot let my campaign be a part of aiding a surrender to terror.… This isn't an easy decision; I hate to lose.… If this were only about me, I'd go on. But it's never been only about me. I entered this race because I love America. And because I love America, in this time of war, I feel I now have to stand aside for our party and our country."