In the 2006 Liberal Democrats leadership election, Sir Menzies Campbell was elected to succeed Charles Kennedy as Leader of the Liberal Democrats, the third-largest political party in the United Kingdom.

On January 5 2006, following a period of heavy speculation about both his leadership and his personal life, party leader Charles Kennedy called for a leadership contest to allow party members to decide if his leadership should continue. On January 7 2006, following public pressure from many prominent Liberal Democrats to stand down, including twenty-five Members of Parliament who publicly announced they would refuse to serve on the party's frontbench if he did not stand aside, Kennedy announced that he would not be standing in the leadership election, resigning as party leader "with immediate effect".

Four candidates declared their intention to stand: Campbell, then interim leader; home affairs spokesman Mark Oaten; the party's President, Simon Hughes; and treasury spokesman Chris Huhne. Oaten garnered little support from colleagues and withdrew from the contest; two days later, he confessed to a sexual relationship with a male prostitute. Nominations for the leadership closed on January 25 2006, and Campbell was announced as the winner on March 2 2006, having won 45% of the first preference votes cast. This rose to 58% when votes cast for third-placed Hughes were excluded and his voters' second preferences were counted.