Bill and Hillary Clinton are the headliners for Senator Tom Harkin’s Steak Fry in September.

“This is the last one,” Harkin said recently, “my 37th and last.”

And it may wind up as the biggest ever. Harkin’s annual fall fundraiser has been a proving ground for presidential candidates of the past. This year’s September 14 event will mark Hillary Clinton’s first appearance in Iowa since her 2008 campaign and it will be seen by many in the Democratic Party as a first step for a 2016 campaign.

Hillary Clinton’s husband was the final speaker at the 2003 Harkin Steak Fry and over 10-thousand people turned out on a hillside in Indianola that year. It rained most of the day, but the sun came out just before the former president took the stage.

“I’ll never forget it,” Harkin said, laughing and shaking his head as he said: “Bill Clinton.”

Harkin ran for president in 1992, but he dropped out of the race in March and endorsed Bill Clinton. In 2008, Harkin did not endorse any of the candidates competing for the Democratic Party’s presidential nomination, but his wife, Ruth, campaigned extensively for Hillary Clinton.

In a prepared statement released today, Senator Harkin said Bill and Hillary Clinton are “close friends” who “have contributed so much good, inspiring leadership to this country.” Harkin talked about the upcoming Steak Fry during a Radio Iowa interview in late July.

“I hope we have a really good last Steak Fry and I think we will. There’s only one thing left to do: pray for good weather,” Harkin said, with a laugh.

This will be Bill Clinton’s fourth appearance at a Harkin Steak Fry. Hillary Clinton spoke at the event in 2007 along with the other Democratic presidential candidates running that year. A farm in rural Madison County was the site of the first-ever Harkin Steak Fry. In 1991, Harkin used the event to launch his own presidential campaign. The 2014 edition of the Harkin Steak Fry will be staged on the balloon field on the east side of Indianola.