Sen. John McCain (R-Ariz.) launched into a stinging critique of President Barack Obama's foreign policy on behalf of GOP presidential candidate Mitt Romney on Monday, just hours ahead of the third and final presidential debate.

Speaking to reporters about the issue of the night, McCain quickly went on the offensive, blasting the president's "failed leadership" in the global arena.

"Look at our relations with Russia. Four years and no progress with Iran on nuclear weapons, strained relations with Israel, al Qaeda coming back strongly in Iraq, things deteriorating in Afghanistan," McCain said, according to AFP. "The foreign policy debate is about leadership, how the president can answer for our failed leadership throughout the world."

The former GOP presidential candidate went on to slam Obama for his perceived inaction in Syria, where seemingly unending violence between rebels and the Bashar al-Assad regime has left more than 34,000 people dead.

"I think he has projected a position of weakness and a position of a lack of leadership, as he calls it: leading from behind. How do you justify over 30,000 people being massacred in Syria, and I've heard him speak up on their behalf once? Once," McCain said, according to the Guardian. "What has this administration done? Absolutely nothing. And, just as many of us predicted, it's beginning to spill over into Lebanon, into Jordan, into the other countries in the region and we are on the verge of a serious crisis."

Seeking to chip away at what many perceive as the apex of Obama's first-term foreign policy achievements, McCain also attempted to play down the president's role in the mission to take out al Qaeda leader Osama bin Laden. Building on his earlier comments, the Republican also suggested that al Qaeda was again gaining power, not losing it as Obama has claimed.

"I think that all Americans give the president credit for the elimination of OBL," McCain said, according to BuzzFeed. "And then he should take credit for the abject failure throughout the Middle East. Al Qaeda is resurgent throughout Iraq, Afghanistan, all of North Africa, Libya, Mali. They’re returning because we’re weak."

The senator went on to decry what he explained as a broader lack of "class," and "desperate" tone exhibited by Obama during the second presidential debate last week.

McCain later hit the administration's handling of the attack on a U.S. consulate in Libya that claimed the lives of four Americans, including Ambassador Christopher Stevens.

"It's ridiculous and outrageous to blame it on intelligence sources when facts are obvious before your very eyes," McCain said in an interview with CNN. "So it's ridiculous. It's an attempt to put the blame -- first they threw Hillary under the bus. Now I guess they're going to throw the CIA under the bus."

A report in the Washington Post over the weekend found that that the CIA had believed the attack was linked to an anti-Islam film. Obama and other administration officials used this explanation in addressing the fallout from the incident, but subsequent reports that the siege was actually a planned attack by militants have led Republicans to argue that the president and other officials deliberately misled the public about the nature of the incident.

McCain remained unconvinced that the administration's differing answers on the episode were consequences of changing intelligence. He said Obama was responsible for an "unacceptable screw-up" and scoffed at the idea that there could have been any honest confusion among various officials tasked with discussing the attack.

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  • Paul Krugman

    <a href="http://krugman.blogs.nytimes.com/2012/08/10/culture-of-fraud/">The Nobel Prize-winning economist wrote</a> in a New York Times blog post in August: "Romney’s tax plan is now a demonstrated fraud — big tax cuts for the rich that he claims would be offset by closing loopholes, but the Tax Policy Center has demonstrated that the arithmetic can’t possibly work."

  • Matt Taibbi

    Matt Taibbi, contributing editor to Rolling Stone, <a href="http://www.rollingstone.com/politics/blogs/taibblog/the-vice-presidential-debate-joe-biden-was-right-to-laugh-20121012">wrote in a recent blog post </a>: "If you're going to offer an across-the-board 20 percent tax cut without explaining how it's getting paid for, hell, why stop there? Why not just offer everyone over 18 a 1965 Mustang? Why not promise every child a Zagnut and an Xbox, or compatible mates for every lonely single person?"

  • Larry Summers

    Harvard economist Larry Summers, a former top adviser to President Barack Obama, <a href="http://www.huffingtonpost.com/2012/10/11/larry-summers-romney-tax-plan_n_1958982.html">recently compared Mitt Romney's tax plan</a> to a hamburger and ice cream diet. He said: "It’s easy to say that 'My plan is to eat ice cream sundaes and chocolate cake and hamburgers as much as I want, my plan is to lose 60 pounds, and my plan is to avoid painful exercise, and those are all my objectives and I'm committed to every one of them.'"

  • The Tax Policy Center

    <a href="http://www.taxpolicycenter.org/publications/url.cfm?ID=1001628">The Tax Policy Center</a>, a nonpartisan, nonprofit think tank, <a href="http://www.huffingtonpost.com/2012/09/11/romney-tax-plan-middle-class_n_1874113.html">recently concluded</a> that Mitt Romney's tax plan is mathematically impossible without raising taxes on the middle class.

  • Josh Barro

    <a href="http://www.bloomberg.com/news/2012-10-12/the-final-word-on-mitt-romney-s-tax-plan.html">Bloomberg View columnist Josh Barro wrote</a> in a recent column that the six studies that the Romney campaign uses to claim the candidate's tax plan is mathematically possible "individually and collectively...fail the task."

  • Mark Zandi

    <a href="http://thinkprogress.org/economy/2012/10/12/1004921/zandi-romney-tax-plan/">Mark Zandi</a>, chief economist at Moody's Analytics, recently said on CNN that when it comes to Romney's tax plan, "the arithmetic doesn't work as it is right now."

  • Ezra Klein

    <a href="http://www.washingtonpost.com/blogs/ezra-klein/wp/2012/08/04/romney-tax-plan-on-table-debt-collapses-table/">Washington Post columnist Ezra Klein wrote in August</a> that "the Tax Policy Center’s analysis has removed all doubt" that Romney's tax plan is mathematically impossible.

  • David Frum

    <a href="http://www.thedailybeast.com/articles/2012/10/11/vice-presidential-debate-live-blog.html">David Frum</a>, contributing editor at Newsweek and The Daily Beast, recently wrote: "Romney's tax cut plan doesn't work. I'm a Republican, I support Romney, etc. But you can't cut that much in such a stagnant economy and expect to break even. Even with a deductions cap, it just won't happen."

  • Catherine Rampell

    Catherine Rampell, economics reporter at The New York Times, wrote of the <a href="http://economix.blogs.nytimes.com/2012/10/01/the-math-on-the-romney-ryan-tax-plan/">the Romney campaign's tax promises</a> in a recent blog post: "Not <em>all</em> of those principles can coexist so long as basic arithmetic survives."