He attended the University of Wisconsin–Madison, but interrupted his studies in 1942 to enlist in the United States Army for service in World War II.

[2] In 1950, Reynolds entered the race for United States House of Representatives in Wisconsin's 8th congressional district, challenging three-term incumbent Republican John W.

[3] Reynolds unanimously received the Democratic nomination, but fell far short of Byrnes in the general election, taking only 38% of the vote.

At the urging of Democratic State Party Chairman Patrick Lucey, Reynolds entered the race for Attorney General in 1958, hoping to unseat incumbent Stewart G.

[8] Reynolds, however, earned the enthusiastic endorsement of influential Madisonians, Arthur J. Altmeyer, known as the father of the Social Security Act,[9] and James Edward Doyle, the former chairman of the state party.

In his capacity as Attorney General of Wisconsin, Reynolds brought a lawsuit in federal court to compel the Legislature to fulfill that obligation.

[15] The court accepted his recommendation and dismissed the suit, though they did warn that the issue could be renewed if no redistricting plan was passed by August 1963.

The Legislature passed a new map, but Reynolds rejected it as failing to provide equal representation for all Wisconsin voters.

Finally, in July 1963, the Legislature attempted to circumvent Reynolds by passing their redistricting law as a joint resolution.

[17] A last-ditch effort was made by the Legislature, but their final attempt was again rejected by Governor Reynolds, who criticized the partisan bias of the map, calling it "a fraud upon the people".

[19] The new plan was embraced by Governor Reynolds, who called it, "the culmination of my four-year fight for equal voting rights for the people of the state of Wisconsin.

Reynolds opposed segregationist George Wallace in the 1964 Democratic presidential primaries who would otherwise have run unopposed, as President Lyndon B. Johnson refused to say he was in the race.

[citation needed] Like the other "favorite sons" who ran in Johnson's place (such as Matthew E. Welsh and Daniel Brewster), he won his state's primaries.