[3][4] In the summer of 1993, Cunningham attended American University and interned on Capitol Hill for a subcommittee chaired by Senator Carl Levin.

[11] In November 2000, Cunningham was elected to represent the 23rd Senate district of the North Carolina General Assembly, which included parts of Davidson, Rowan, and Iredell Counties.

[19][20] Cunningham left WasteZero in March 2020, shortly after winning the Democratic nomination, but continues to work for the company as an independent contractor.

[23][24][25] Retired NATO Supreme Allied Commander General Wesley Clark endorsed Cunningham, saying that he would be "the first veteran of the wars in Iraq and Afghanistan to serve in the U.S. Senate", as did the state's largest organization of teachers, the North Carolina Association of Educators.

[28] Cunningham originally declared his candidacy for lieutenant governor of North Carolina,[29][30] but he withdrew in June 2019 to run for the United States Senate seat held by Thom Tillis instead.

[31] During the primary, a Republican-allied Super PAC spent $3 million on ads attacking Cunningham and supporting left-wing state Senator Erica Smith in order to "amplify fault lines in the Democratic party.

[35] Cunningham stated his support of the Affordable Care Act and called for the expansion of Medicaid in North Carolina, as well as a public health insurance option.

[32] In July 2020, incumbent Republican Thom Tillis claimed Cunningham had been "silent" on the issue of defunding the police, saying, "I assume his silence is consent."

[40] On October 3, the New York Times wrote that the race had fallen into "utter mayhem" within a period of a few hours after Tillis tested positive for COVID-19 and Cunningham admitted to exchanging sexual text messages with a woman who was not his wife, damaging an image that leaned heavily on his character and military service.

[44][45][46][47] Following the disclosure of the texts and his response, Cunningham "assumed a position of complete radio silence, withdrawing from the campaign trail [save] for a last-minute appearance in Charlotte with the rapper Common".