WASHINGTON — Joe Sestak, a freewheeling former Pennsylvania congressman, U.S. Senate candidate, and three-star admiral who often clashed with Democratic insiders, is running for president.

Sestak, of Delaware County, launched a campaign website at midnight Saturday dubbing himself “Admiral Joe” and announcing a kickoff event Sunday afternoon in Waterloo, Iowa.

“I’d like to be that president who serves the American people the way they deserve to be served,” Sestak, 67, wrote in an email to The Inquirer.

>>READ MORE: For Sestak, the path to Senate runs 422 miles

The unpredictable Sestak is the 24th Democratic entrant into a primary free-for-all that has drawn contenders from all over the map in terms of geography, politics, experience, and public profile.

“I believe that what Americans most want is someone who is accountable to them, above self, above party, above any special interest,” Sestak continued in his email, echoing the themes of a campaign video that launched Sunday. “A president who has the depth of global experience to restore America’s leadership in the world to protect our American Dream at home … and one who is trusted to restructure policies where too many see only the growth of iniquity, not of the economy.”

In keeping with his unusual methods, Sestak’s announcement surprised even some longtime supporters and former campaign aides, who were blindsided by his decision to reenter politics on the biggest possible stage.

Sestak served two terms in Congress before running for U.S. Senate in 2010. Defying the Democratic establishment, he beat then-U.S. Sen. Arlen Specter in a primary, after Specter had switched parties, only to narrowly lose to Sen. Pat Toomey (R., Pa.) in the general election.

Sestak ran for Senate again in 2016 — walking 422 miles across Pennsylvania to reintroduce himself to voters — but party insiders recoiled at his independent-minded and unorthodox style and rallied behind Katie McGinty, who beat Sestak in the Democratic primary.

He has had almost no public profile since, but is now joining the sprawling field.

Sestak is the first person who served in a Pennsylvania office to join the race, though former Vice President Joe Biden has stressed his Scranton roots and is basing his campaign in Philadelphia, and former Colorado Gov. John Hickenlooper was raised in Narberth.

Sestak’s campaign pitches have always been tied to his military service, and his speeches laden with Navy metaphors. He served as a three-star admiral in the Navy, commanding an aircraft carrier group that operated in Iraq and Afghanistan, and was an adviser on the National Security Council in the Clinton White House. He usually campaigned in an olive flight jacket.

Sestak’s website was set to include five introductory videos.

He joins the race after others have been jockeying for months, and just days before the first Democratic debate, which he will not be part of. (Candidates had to meet certain fund-raising and polling targets weeks ago to qualify.)

He said he delayed his entry into the presidential race while his daughter successfully battled brain cancer, which returned after she first beat it at age 4.