Mitt Romney, sensing a fresh opportunity to attack President Obama's first-term record, on Monday questioned the administration's handling of a terrorist attack on the U.S. consulate in Libya, saying it raised questions about the president's competence as commander in chief.

For most of the campaign, Romney has focused on Obama's failure to revive the economy. But with questions mounting about the administration's preparedness for -- and reaction to -- the Sept. 11 terrorist attack on the U.S. consulate in Libya, Romney is calculating that Obama is now vulnerable in the area that had been his strongest suit, foreign affairs.

In an opinion piece penned in the Wall Street Journal, Romney framed the surge in violence in the Middle East and Northern Africa and anti-American sentiment across the globe as evidence that Obama has failed to lead effectively.

"These developments are not, as President Obama says, mere 'bumps in the road,' " Romney wrote. "They are major issues that put our security at risk. Yet amid this upheaval, our country seems to be at the mercy of events rather than shaping them."

The Romney campaign says it's unlikely that foreign policy will eclipse its focus on the economy, but the issue does bolster Romney's effort to shape the election as a referendum on the president's first term.

"Really, it's part of a broader argument that Obama is in over his head," a Romney adviser told The Washington Examiner. "This is just the latest Obama failure. He didn't fix the economy. Things are worse overseas. He doesn't have any legs left to stand on."

Romney also plans to make a major foreign policy address sometime after the first presidential debate on Wednesday, his campaign confirmed.

While Republicans traditionally have an edge on national security issues, Romney is up against a president with a run of foreign policy successes, including the killing of Osama bin Laden and a number of other al Qaeda leaders.

"If Mitt Romney wants to focus on foreign affairs, we'll be glad to have that debate," an Obama campaign aide said. "The president's record speaks for itself."

Romney has suffered several self-inflicted wounds on the international front, including his suggestion that London wasn't ready to host the Olympics and rushing out a partisan statement on the Libya attack before it was revealed that a U.S. ambassador and three Americans were killed there.

"They have all the way along seemed to feel like it's necessary to counter Obama's advantage on national security," said Heather Hurlburt, executive director of the National Security Network, a progressive group. "But every time [Romney] pivots back to national security, voters look at his past mistakes. I don't see what it buys him."

The Obama administration originally claimed the attack in Libya was an angry reaction to an anti-Muslim video that sparked smaller, less violent protests in Egypt and elsewhere. But administration officials admitted last week that the attack was a planned terrorist strike and possibly tied to al Qaeda.

"I think there's certainly fertile ground there; Romney can really make a case that Americans could find persuasive and compelling," said Victoria Coates, former foreign policy adviser for Texas Gov. Rick Perry and adjunct fellow at the Foundation for the Defense of Democracies. "I would encourage them to do so. He should have done it sooner."