WAYNE, Pa. — Two weeks after sharply criticizing the Obama administration for its handling of the attack on the U.S. consulate in Libya, Mitt Romney said Friday that it was “premature” to cast judgment on how his Democratic rival handled the developments in Libya and said he would wait for the results of an investigation.

It was a clear tonal shift on the part of the Republican presidential nominee.

As the attacks on the U.S. Embassy in Cairo and the U.S. Consulate in Benghazi, Libya, were unfolding earlier this month, Romney released a late-night statement taking issue with a statement from U.S. diplomats in Cairo. Romney’s release went out before he knew that the attacks in Libya had taken the lives of the U.S. ambassador and three other Americans.

The U.S. diplomats in Cairo had taken issue with an anti-Islamic video posted on YouTube, stating that the embassy opposed “continuing efforts by misguided individuals to hurt the religious feelings of Muslims — as we condemn efforts to offend believers of all religions.”

Romney had pinned those comments on President Obama, arguing that the president’s administration was making an “apology for America’s values.” The president charged Romney with politicizing a tragedy; and even some of Romney’s own Republican colleagues took issue with what he had said.

Romney was much more measured during an impromptu news conference Friday on his plane as he traveled from a campaign rally in Wayne, Pa. — his first in the Keystone State since the summer — to Boston, where he plans to spend the weekend preparing for his first debate with Obama, which is Wednesday at the University of Denver.

Though Romney’s Republican colleagues have accused the Obama administration of obscuring details about the security situation in Libya and whether U.S. officials could have done more to prevent what is now believed to have been a terrorist attack there, Romney said he would wait to see the results of the investigation that has been suggested by Sen. John F. Kerry (D-Mass.).

“I think with the investigation ongoing it would be premature to describe precisely what the administration did correctly or incorrectly,” Romney told reporters on the plane. “There are a wide array of reports about warnings, and whether they were heeded — we’ll find out whether that was the case or that was not the case.”

Romney said he believed it was clear “that this was a terrorist attack against our diplomats and there was not a spontaneous reaction to a film being shown, apparently on the Internet.”

“There was a great deal of confusion about that from the very beginning on the part of the administration, and whether that was something that they were trying to paper over or whether it was just confusion given the uncertain intelligence reports — time will tell.”

He added that he believed the Obama administration “has responsibility for candor.”

During the news briefing on the plane and during the earlier rally in Wayne, however, Romney did not back away from his criticism that the president has led from behind.

“The Middle East and the world longs for American leadership,” Romney said on the plane. “Leading from behind is not the right course for America. We are increasingly being seen as being at the mercy of events, rather than shaping those events. And that comment is consistent with what’s developed in Iran, in Syria, Libya, Egypt. We can play a more meaningful role in shaping world events.”

Both Obama and Romney spoke by telephone Friday to Israeli Prime Minister Benjamin Netanyahu, who gave a fiery speech at the U.N. earlier this week outlining the threat of a nuclear Iran.

The Obama administration has chafed at Romney’s characterization of its approach toward world events. On Friday, Vice President Joe Biden praised the president in Florida, telling the audience how proud he was “to stand shoulder to shoulder with a guy who has done more for Israel’s physical security than any president of the eight I’ve served with.”

Though Romney has been friends with Netanyahu for several decades, he was not above ribbing his old friend. He noted that Netanyahu had brought a chart to the U.N. to illustrate how close Iran was to obtaining a nuclear bomb.

Netanyahu’s graphic, Romney joked, was “not up to the normal Boston Consulting Group standards,” he said, alluding to his old company.

maeve.reston@latimes.com