During debate preparation, Romney’s advisers looked to the first encounter between Ronald Reagan and President Jimmy Carter in 1980. Answering his first question in that debate, Reagan said: ‘‘Our first priority must be world peace, and that use of force is always and only a last resort, when everything else has failed.’’

Aides also urged Romney to follow Reagan in projecting optimism.

‘‘I'm optimistic about our future,’’ Romney said in his closing statement.

The strategy came as a surprise to some conservatives, who expected Romney to challenge Obama directly on some of the biggest foreign policy issues as he had with the economy, unemployment and debt in their first debate earlier this month. Republican commentators lamented Romney’s use of ‘‘kid gloves’’ against Obama and his failure to challenge Obama on the Sept. 11 attack on the U.S. Consulate in Benghazi, Libya, that killed a U.S. ambassador and three other Americans.

Libya seemed teed-up for Romney after weeks when he and other Republicans had hammered the administration for possible intelligence and security failures and a shifting message on how it happened.

Asked about the attack with the first question of the debate, Romney instead chose to focus on the larger challenges facing a Middle East in the throes of democratic transition and the continued threat posed by al-Qaida and Islamist extremism. After Obama parried by saying he was investigating the attack and going after the perpetrators, one of Romney’s most obvious lines of attack was effectively eliminated from the discussion.

A Romney aide said the Libya issue was already clarified.

‘‘The governor’s made clear in many different forums and interviews that he believes that there are more questions than answers at this point,’’ senior adviser Eric Fehrnstrom said. ‘‘He’s covered that ground.’’

Aides said the candidate wanted to avoid any traps in territory that he was less familiar with, perhaps explaining the Republican’s comfort in allowing the conversation to veer toward education, automobiles, job creation plans and other economic questions.

On many of these issues, Romney has outscored Obama in national polls. On foreign policy, the president has held an advantage. And Romney has struggled to establish his national security credentials after a problematic summer tour overseas that saw him offend his British hosts by questioning their security preparations for the Olympic Games and raise hackles among Palestinians who accused him of racism when he said culture was part of the reason Israelis were more economically successful than they.

___