Former U.N. Ambassador John Bolton — a leading Republican hawk and former top adviser to Governor Mitt Romney — said Sunday that Romney lost in part because he and his party have abandoned their traditional aggressive posture on national security.

"I would have stressed national security issues more," Bolton told WABC's Aaron Klein of Romney's campaign. "I don't fault the Romney campaign alone for that, though. I think the entire Republican party has spent four years making a huge mistake really retreating from its historic role as the main advocate of sound national security policies. And in that sense the campaign's unwillingness to take on Obama's failed foreign and defense policies was symptomatic of the problem of the party as a whole."

Republicans have signaled broad acceptance of President Barack Obama's withdrawal from Afghanistan and Iraq, of deep cuts to defense spending in the congressionally mandated "sequester," and have in fact lately challenged Obama from the left on drone policy.

"I don't know whether that would have won the election or not," Bolton said. "But I think people want a president who is going to go to Washington and defend America's interests internationally. The American people are very pragmatic. They know they are not going to pore over the intricacies of foreign and defense policy. But they expect a president who will stand up for them internationally. And I think they respect that. It's what they've looked for that in presidential candidates. I think Romney could have provided that and I am just sorry we didn't have more of it."