How much weight does Colin Powell’s endorsement of Obama carry?

In 2008, former Secretary of State Colin Powell's endorsement of Barack Obama helped boost then-candidate Obama's standing with independent voters and assuage concerns over his relatively limited experience with national security and foreign policy, reported Bloomberg.

On Thursday, Powell endorsed Obama for a second term in office, after saying earlier this year he was not yet prepared to renew his support for the president. When placed within the larger context of Powell's political career, how much weight does the endorsement carry?

Powell served under three Republican administrations, including the one right before Obama, that of former President George W. Bush.

When Powell was appointed Secretary of State by Bush, Time magazine noted, "Powell, after all, brings to the table a true-blue Horatio Alger story — black kid from the Bronx made good with no special favors — as well as a remarkable track record in the military, an almost unprecedented wealth of goodwill from across the political spectrum and a commanding moral authority."

Initially, Powell was considered a counterweight to the more hawkish conservatives in the Bush administration. While the hawks advocated a military option and aid to the Iraqi opposition in 2001, Powell posed for "smart sanctions" that would allow humanitarian aid but limit military aid, PBS noted.

But Powell's defining moment as Secretary of State — one that haunted his reputation — came when he made the case for invading Iraq in a speech to the United Nations Security Council in February 2003. He alleged that Iraq had weapons of mass destruction which it refused to disarm, citing mounting evidence.

On the 10th anniversary of the Sept. 11 attacks, Powell told Al Jazeera that that information was a "blot on my record."

"It turned out, as we discovered later, that a lot of sources that had been attested to by the intelligence community were wrong," he said. "I understood the consequences of that failure and, as I said, I deeply regret that the information — some of the information, not all of it — was wrong."

Despite the battering his reputation took after his stint as Secretary of State from 2002 to 2005, Powell's approval ratings remained higher than many from the Bush administration in 2009. A CNN/Opinion Research Corporation survey showed that 70 percent of those surveyed had a favorable opinion of Powell in May 2009.

More on GlobalPost: Colin Powell endorses Obama for second term (VIDEO)

Powell has cast himself as a moderate Republican. During the interview in which he announced his endorsement today, Powell said, "I think I'm a Republican of a more moderate mold and that's something of a dying breed, I'm sorry to say."

"But, you know, the Republicans I worked for were President Reagan, President Bush 41, the Howard Bakers of the world, people who were conservative, people who were willing to push their conservative views, but people who recognize that at the end of the day [you've] got to find a basis for compromise. Compromise is how this country runs," he added, according to Slate magazine.

In light of his own career and track record, here are Powell's comments on Romney's foreign policy, in which Powell doesn't have much confidence:

I have concerns about his views on foreign policy. The Governor, who was speaking on Monday night at the debate, was saying things that were quite different from what he said earlier. So I’m not quite sure which Governor Romney we would be getting with respect to foreign policy…

It’s a moving target. One day he has a certain strong view about staying in Afghanistan, but then on Monday night he agrees with the withdrawal. Same thing in Iraq. On almost every issue that was discussed on Monday night, Governor Romney agreed with the President, with some nuances. But this is quite a different set of foreign policy views than he had earlier in the campaign. And my concern, which I’ve expressed previously in a public way, is that sometimes I don’t sense that he has thought through these issues as thoroughly as he should have, and he gets advice from his campaign staff that he then has to adjust to modify as he goes along.

Sen. John McCain, whom Powell endorsed in 2000, before Bush won the primary, said Thursday, "General Powell, you disappoint us and you have harmed your legacy even further by defending what is clearly the most feckless foreign policy in my lifetime," according to The Hill.

Obama adviser Dan Pfeiffer said that Obama was "very appreciative" of Powell's endorsement, according to ABC News.

"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."

The Washington Post suggested that while Powell's endorsement is still potentially powerful, it doesn't have the element of surprise that his 2008 endorsement of Obama had.

"Powell remains among the most popular and trusted figures operating in American politics, which should give his words some heft," said The Post, but it noted, "it’s hard to see the endorsement having the same sort of lift that it did four years ago."