SPRINGFIELD, Ill. - On a weekend dedicated to honoring military service, Illinois Senate candidate Mark Kirk has acknowledged he contended that he was named the U.S. Navy's intelligence officer of the year, an award he never won.

The Republican's disclosure comes at a time when politicians face heightened scrutiny of their military records, thanks to a Connecticut Democrat who wrongly said he had served in Vietnam.

Kirk, who is in a tough race for President Obama's old Senate seat, said in a statement that the award was simply misidentified in his official biography. He said he would correct the biography to show that it was his unit, not him personally, that won the 1999 award.

Kirk, a five-term representative, said that his leadership helped the unit earn the honor and that he remained proud of his service.

His incorrect claim has been repeated frequently. His campaign website and his official congressional site have been updated, but previously said he was intelligence officer of the year. A spokesman said earlier this year that Kirk won the award, and news reports using that description date to at least 2003.

His Democratic opponent, Illinois state treasurer Alexi Giannoulias, suggested that Kirk was intentionally inflating his credentials. Kirk's responses to the issue "raise even more questions than they answer about a troubling pattern from a typical Washington politician," Giannoulias spokeswoman Kathleen Strand said.

Kirk's campaign criticized the Washington Post story that first revealed he had not won the award. The newspaper said it began asking questions after hearing from a Giannoulias representative.

Giannoulias has had his own political troubles since the shuttering of his family's bank, where he once worked. Republicans have tried to capitalize on that failure because winning the seat would be a plum prize that they've long counted on Kirk to bring home.

Republicans held the seat for six years before Obama won it in 2004. Sen. Roland Burris, who was appointed to Obama's seat by the scandal-plagued former Illinois Gov. Rod Blagojevich, opted not to run for a full term.

The admission that Kirk had overstated his record came two weeks after a national furor over Connecticut's Democratic Senate candidate Richard Blumenthal, who incorrectly said in several speeches that he had served in Vietnam. Blumenthal served in the Marine Reserves during the Vietnam War, but never left the United States. He sometimes spoke as if he had been stationed in Vietnam, a practice that became a campaign controversy.