[2] Before running for office, Hubbell served as Chair of the Younkers retail department stores in the 1980s and President of Equitable of Iowa.

While at Equitable, he led day-to-day operations and strategic initiatives and was given credit for "orchestrating a revival of the once sleepy corporation."

[6] In 2009, Governor Chet Culver appointed Hubbell as Acting Director of the Department of Economic Development of Iowa to help clean up hundreds of millions of dollars in waste related to a film tax scandal.

On November 14, 2017, Iowa Starting Line released a poll showing Hubbell leading the Democratic primary earning 22% support, 9% more than any other candidate.

A later poll by The Des Moines Register showed similar results,[15] with Hubbell earning the highest favorability of any Democratic candidate.

The more than $3 million fundraising total set an off-election year record in the Democratic primary for Governor of Iowa.

[16] He faced the Republican incumbent, Kim Reynolds and the Libertarian candidate, Jake Porter, in the general election, which was held on November 6, 2018.