Updated

Illinois Senate candidate Mark Kirk is acknowledging that he falsely claimed to have received the U.S. Navy's Intelligence Officer of the Year award after his opponent's campaign started challenging Kirk's resume.

Kirk, a five-term Republican representative, said his official biography "misidentified" the award.

Kirk did not win the Intelligence Officer of the Year prize in the late 1990s -- awarded by the U.S. Navy -- but did receive the "Rufus Taylor Intelligence Unit of the Year" award for outstanding support provided during Operation Allied Force.

The award was given to the unit that Kirk led in Aviano, Italy, rather than to him individually.

"At Aviano, I took charge of four deployed squadron's intelligence assets and personnel and forged them into a combat intelligence action team -- the largest EA-6B intelligence shop in the history of naval aviation. Our team supported combat flight operations 24 hours a day, 7 days a week, and provided more than 150 combat flight intelligence briefings for more than 80 aircrew," Kirk wrote Friday.

"My service during the Kosovo conflict remains one of the proudest periods of my life," he wrote. "It was one of the honors of my life to lead the Intelligence Division Electronic Attack Wing Aviano, Italy -- and I am very proud of this award."

The Washington Post was first to expose the error after complaints from a representative of Illinois state Treasurer Alexi Giannoulias, Kirk's Democratic opponent in the Senate race.

Kathleen Strand, communications director for the Giannoulias campaign, told the Post on Friday that Kirk "is lying or embellishing his military record," making him "the worst kind of Washington politician."

The correction comes shortly after Connecticut Attorney General Dick Blumenthal was called out by Republican Linda McMahon, his presumptive challenger for the U.S. Senate seat, for saying he had served in Vietnam, when he was a Marine reservist who never left the United States for war.

Like Blumenthal's misstatements, The Post learned that Kirk misrepresented his award on more than one occasion, including in a March 2002 hearing on Capitol Hill in which Kirk said, "I was the Navy's Intelligence Officer of the Year," claiming his special qualifications justified his participation in a discussion on national security spending.

Kirk, who is currently a reservist as well as co-chairman of a House Appropriations Committee working group on electronic warfare, has won several honors, including two Navy and Marine Corps Commendation Medals, a Joint Meritorious Unit Award, a Navy Unit Commendation, a Meritorious Unit Commendation and a National Defense Service medal.

Recent polls show Giannoulias closing in on Kirk despite Giannoulias' family bank being seized by federal regulators last month.

Eric Elk, a spokesman for Kirk's campaign, said Giannoulias is in no position to attack Kirk's military record.

"Alexi Giannoulias is a failed mob banker whose reckless lending practices cost the FDIC $394 million when they closed his family bank and he cost Illinois families tens of millions in losses from the state's college savings fund," Elk said in a blog posting on Saturday.