WASHINGTON — Sen. Cory Booker is heading to Iowa this fall, a move that will only further fuel speculation that he is preparing a run for president.

The New Jersey Democrat will be the keynote speaker at an Oct. 6 gala in Des Moines, Iowa's state Democratic Party announced Saturday. With Iowa's prominence in presidential politics — its caucuses are the first contests in the fight for nominations — the trip is the strongest signal yet that Booker has an eye on the White House.

Booker, one of several Democrats seen as potential challengers to President Trump in 2020, has been traveling the country to campaign for fellow Democrats on the ballot this year. But he has avoided high-profile stops in places like Iowa and New Hampshire, where every visit by an ambitious figure carries presidential implications.

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Booker has deflected questions about his own political plans, saying he is focused on this year's midterms, but he has not ruled out running for president, and grabbed the national spotlight last week by sparking a confrontation with Republicans over Supreme Court nominee Brett Kavanaugh.

"The 2018 election is the most important of my lifetime," Booker, 49, said in a news release announcing the gala. "I've been traveling all across the country this year to campaign for Democrats and discuss the urgency of this moment, and I'm excited to come to Iowa in October to support an incredible slate of inspiring candidates."

Iowa's Democratic state chairman, Troy Price, said: "Senator Booker represents a future-driven vision for our party and our nation that has inspired millions. … We hope that his message will be the fuel Iowa Democrats need to put our candidates over the top in November."

Booker, a former mayor of Newark who was well-known even before he arrived in the Senate, also got national political exposure in 2016 as he traveled the country as a prominent surrogate for Hillary Clinton.