He married second-generation Japanese American Jo Oyama in 1968, just after the Supreme Court case of Loving v. Virginia struck down prohibitions against interracial marriage.

Wisconsin never had a law prohibiting interracial marriage, but the couple lived for a time in Alabama, where Miller had been stationed with the Air National Guard.

In the general election, he faced Republican Madison consultant Kevin Miller, and won 68% of the vote in the Democrat-friendly district.

In 2004 he seized an opportunity to run for the Wisconsin State Senate in the 16th district, where incumbent Charles Chvala was facing criminal indictment.

[5] The 2010 elections gave Republicans full control of state government with Scott Walker as Governor and new majorities in the Legislature.

Miller was chosen as the new leader for Senate Democrats in the minority, and expressed interest in working with the new majority to advance the business of the state.

[6] However, Governor Walker's Budget Repair Bill—ending collective bargaining rights for public employee unions—was seen as so radical that it provoked massive protests at the State Capitol.

As the bill was nonetheless being passed during the evening hours of March 9, 2011, Miller commented acidly, "In 30 minutes, 18 senators undid 50 years of civil rights".