[9] In post-public office life, Duncan serves as a frequent commenter on CNN, and is a public speaker with The Harry Walker Agency.

[11] In the Republican primary, he narrowly defeated former legislator Tom Knox, who held the seat before running for State Insurance Commissioner in 2010.

[12] Duncan's campaign emphasized creating private sector jobs, reducing government spending, and supporting conservation efforts at Lake Lanier.

As a state legislator, he helped lead efforts to pass Michael’s Law, a bill that forbids individuals under the age of 21 from working as bar bouncers.

[18] The runoff election focused largely on Shafer's record at the capitol and a number of ethical questions surrounding his candidacy.

[22] He defeated Democratic nominee Sarah Riggs Amico in the general election, receiving nearly 52% of the vote and avoiding another runoff.

[24] As lieutenant governor, Duncan highlighted efforts by the Kemp administration on healthcare policy, and stated his wish for Georgia to become the "technology capital of the East Coast".

Days later, Duncan said during a CNN interview that momentum for the legislation grew from "the fallout from the ten weeks of misinformation that flew in from former President Donald Trump.

[29] An October 2021 trip to New Hampshire to promote his book GOP 2.0, which outlines plans for a post-Trump future for the Republican Party, fueled speculation in his home state that Duncan may be positioning himself to run for president in 2024.

[32] In May 2024, during the lead-up to the 2024 presidential election, Duncan wrote an opinion piece titled "Why I'm Voting for Biden and other Republicans should, too", which appeared in the May 6, 2024 edition of the Atlanta Journal-Constitution.

Duncan described Biden as a "decent person I disagree with on policy", which he contrasted with Trump, whom he characterized as "a criminal defendant without a moral compass".

[34] Duncan urged Republicans to support Harris' presidential campaign,[35] giving a speech directed to them at the Democratic National Convention.