TAMPA, Fla. - Four years after he broke with the Republican Party to endorse then-Senator Obama, former Secretary of State Colin Powell announced today he is endorsing his reelection, saying he's concerned Mitt Romney's foreign policy is a "moving target."

"I voted for him in 2008 and I plan to stick with him in 2012, and I'll be voting for he and for Vice President Joe Biden next month," Powell told CBS News.

Powell cited the president's handling of the economy and foreign policy successes in explaining his decision.

"When he took over the country was in very, very difficult straits, we were in one of the worst recessions we had seen in recent times, close to a depression," Powell said of the economy Obama inherited from his former boss George W. Bush. "We were in real trouble."

"I saw over the next several years stabilization come back in the financial community, housing is now starting to pick up after four years, it's starting to pick up. Consumer confidence is rising. So I think generally we've come out of the dive and we're starting to gain altitude," Powell explained. "It doesn't mean we are problem solved, there are lots of problems still out there. The unemployment rate is too high. People are still hurting in housing. But I see that we are starting to rise up."

Powell, who served as secretary of state from 2001 to 2005, praised Obama for ending the war in Iraq and winding down the war in Afghanistan, adding that he "did not get us into any new wars."

The retired four-star general went on to call Obama's actions to protect the U.S. from terrorist threats "very, very solid."

Powell said he has the "utmost respect" for Mitt Romney but was concerned about his shifting foreign policies. "The governor who was speaking on Monday night at the debate was saying things that were quite different from what he's said earlier, so I'm not quite sure what Governor Romney we would be getting with respect to foreign policy," he said.

He also took issue with Romney's economic proposals. "As I listen to what his proposals are especially with respect to dealing with our most significant issue, the economy, it's essentially let's cut taxes and compensate for that with other things. But that compensation does not cover all of the cuts intended or the new expenses associated with defense," he said.

The announcement came as a surprise to the president and his campaign, which was not given any heads up or indication that Powell was going to endorse.

The president is "very appreciative" of the endorsement, Obama adviser Dan Pfeiffer told reporters traveling with the president today.

"He's an American hero," Pfeiffer said. "And his critique about Governor Romney's approach on foreign policy is something, as people make decisions about this election in the remaining 12 days that could certainly have some influence."

Obama called Powell this morning and thanked him personally for his support.