A member of the Republican Party, he was the 43rd governor of Wisconsin, ascending from the Lieutenant Governorship when Tommy Thompson resigned in 2001 to accept appointment as U.S. Secretary of Health and Human Services.

[citation needed] In 1967, he attended a youth leadership program, Badger Boys State, as a representative chosen from Lowell P. Goodrich High School.

McCallum won the Republican nomination for the United States Senate in 1982, but lost in the general election to incumbent William Proxmire.

During his 10 years (1976–1986) as state senator, McCallum was allied with the New Republican Conference, a now-defunct movement of fiscally conservative, but socially liberal, GOP activists.

[7] McCallum's legislative accomplishments included increasing penalties for drunk driving offenses and assaults on prison guards; creating a health insurance risk pool for people considered uninsurable; sunsetting outdated legislation; and indexing individual income taxes to account for inflation.

[10] As the Wisconsin governor, McCallum was cited by the Wall Street Journal during the economic slowdown in 2001 as being one of the 'political tough guys' for balancing the budget without raising taxes.

The public and private partnership was designed to increase awareness of business financing options by engaging statewide networks and professional associations.

[14] The company is a non-profit based in Texas that matches charitable corporate donations of surplus food and supplies with organizations that need them.