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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