Krantz has served as a Member of Parliament since the 2006 election. In the parliament he was a member of the Committee on the Constitution and the War Delegation from 2002 to 2006. Since 2006 he is a member of the Committee on Health and Welfare and a deputy member of the Committee on Civil Affairs, Committee on Cultural Affairs, Committee on Social Insurance and the Committee on European Union Affairs. He is also a member of the board of the Liberal People's Party and a deputy member of board of Riksrevisionen.