President Barack Obama called Vice President Joe Biden shortly after Thursday's vice presidential debate, and told reporters that he "could not be prouder" of his running mate.

"I'm going to make a special point of saying I thought Joe Biden was terrific," he told reporters after Air Force One landed near Washington. "I could not be prouder of him. I thought he made a very strong case. And you know I really think that his passion for making sure that the economy grows for the middle class came through so I'm really proud of him."

It is highly unusual for Obama to approach reporters in this fashion after deplaning.

Obama also posted a tweet to his official Twitter feed after the debate.

"Tonight proved once again that you won't find a better and more tireless advocate for the middle class than @JoeBiden. -bo #TeamJoe," he wrote.

Obama was to watch at least part of the debate while flying back from Florida, where he held an earlier campaign fundraiser in Miami.