Continuing her association with Hillary Clinton, Tanden was an unpaid adviser to Mrs. Clinton’s successful 2016 primary season nomination campaign and unsuccessful general election campaign in opposition to Republican candidate Donald Trump, while also running the Center for American Progress. Tanden was considered a candidate for a top White House job, had Mrs. Clinton won the presidency. After Clinton secured the Democratic nomination for president in 2016, Tanden was named to her transition team.
In 2016, a hacker gained access to John Podesta's private emails (aka the Podesta emails), some which were emails exchanged with Tanden. In one exchange, on August 11, 2015, while discussing news that Harvard University law professor Lawrence Lessig was exploring a bid for the Democratic nomination, Tanden wrote of Lessig, "I fucking hate that guy." Lessig responded to the incident by saying that while he supported whistle blowing and a pardon of Edward Snowden, Tanden should not have to be burdened with having her private emails scrutinized and that it was not in the public interest. Tanden called the release of her personal communications, which often feature her blunt private assessments, a painful experience to endure.
After the 2016 election and Clinton’s loss, Tanden refocused the work of the Center for American Progress, aiming to have the think tank, and especially its advocacy arm (the Center for American Progress Action Fund), serve as a “central hub for Trump resistance” as well as playing a leading role in shaping the healthcare debate within the Democratic Party.