Launching his manifesto, Mr Huhne said he was "passionately" against the war and "not afraid to show my opposition by marching with Charles Kennedy and other Liberal Democrats".
His remark was clearly directed at Sir Menzies, who had warned Mr Kennedy that marching against the war risked making him appear anti-American.
Mr Hughes also had a dig at Sir Menzies, urging the party not to opt for a "safe pair of hands" or the "steady the ship option" in the face of the slump in Liberal Democrat support.
Mr Hughes said the party's foreign policy, Sir Menzies' responsibility, should be clearer.
Both Mr Huhne and Mr Hughes called for British troops to be pulled out of Iraq by the end of the year, a timetable Sir Menzies' allies have dismissed as "populist".
Mark Oaten, the Liberal Democrat MP for Winchester and former leadership contender, was yesterday given the "unanimous" backing of his constituency party. Mr Oaten resigned as the party's home affairs spokesman last month after allegations about his private life.