DES MOINES, Iowa — On the eve of her most recent trip to Iowa, Hillary Clinton received perhaps the most coveted Democratic endorsement in the state: the backing of former U.S. Senator Tom Harkin.
Harkin, a favorite of progressive Democrats, threw his support behind the former Secretary of State in an op-ed in the Des Moines Register.
"As Democrats, we're fortunate to have a slate of candidates that are all fine individuals, but we need a fighter who has a record of getting things done and the vision for the future that will build on the progress we've made," he wrote.
"For my wife, Ruth and I, that candidate is Hillary Clinton."
The nod from the influential Democrat comes as Clinton contends with a surge of momentum by rival Democratic candidate Sen. Bernie Sanders of Vermont, who is generating excitement from the party's liberal wing. Clinton also faces a continuing firestorm over her use of a personal email server for official business during her tenure as Secretary of State.
In a recent CNN/ORC poll of Iowa Democrats, Clinton won the support of 50%, compared to 31% for Sanders.
Harkin served in the United States Senate for 30 years beginning in 1985 and he only recently retired at the start of 2015. Beloved by Democrats in Iowa, he carries perhaps the most influence within the party in the Hawkeye State. He endorsed Howard Dean, a favorite of liberal activists, in 2004. In 2008, he declined to endorse either Clinton or Barack Obama before the caucuses.
"There are few people who have done more to build the Democratic party in Iowa over the years than Tom Harkin," explained Sam Roecker, a Democratic strategist in Iowa.
"He has been a leader for Democrats in Iowa for decades."
Harkin noted in his op-ed that he shares "many of the same deeply-held beliefs" as Hillary Clinton, highlighting his views on providing access to quality and affordable healthcare, ensuring universal pre-kindergarten to families, and building a "clean-energy economy."
Harkin was also well-known for hosting an annual political fundraiser, The Harkin Steak Fry, which drew Democratic candidates for president every four years. At the final steak fry in 2014, Secretary Clinton spoke —along with her husband President Bill Clinton—and said to cheers, "I'm baaack," upon returning to Iowa.
Ultimately Roecker noted that caucus goers will look to Senator Harkin's endorsement for "guidance" but that Democratic Iowans will still "do their due diligence to get to know all of these candidates."
Hillary Clinton will speak at the Annual Iowa Wing Ding dinner at the history Surf Ballroom tonight along with the other Democratic candidates for president, and she will most likely make an appearance at the Iowa State Fair on Saturday, though she will not speak on the Des Moines Register SoapBox.
NBC's Carrie Dann contributed to this report, which first appeared on NBCNews.com.