This photo taken on September 8, 2004, shows Australian Prime Minister John Howard (L) sharing a light moment with his finance minister Peter Costello (R) after speaking to the party faithfull during a rally in Melbourne's eastern suburbs. Costello announced his retirement from politics on June 15, 2009, ending intense speculation he would challenge for leadership of the opposition Liberal Party. He was Australia's longest-serving treasurer after an 11-year stint under ex-prime minister John Howard, said he would not contest another election following the party's 2007 defeat. Getty Images logo Getty Images 5 months ago

This photo taken on September 8, 2004, shows Australian Prime Minister John Howard (L) sharing a light moment with his finance minister Peter Costello (R) after speaking to the party faithfull during a rally in Melbourne's eastern suburbs. Costello announced his retirement from politics on June 15, 2009, ending intense speculation he would challenge for leadership of the opposition Liberal Party. He was Australia's longest-serving treasurer after an 11-year stint under ex-prime minister John Howard, said he would not contest another election following the party's 2007 defeat.