WASHINGTON -- President Obama's choice of former GOP senator ChuckHagel to lead the Defense Department likely sets up a contentiousnomination fight in the Senate.

Obama plans to nominate Hageltoday to lead the Pentagon as Defense secretary, according to twoofficials familiar with the nomination process. Both officials spoke oncondition of anonymity because it had not been officially announced.

SenateMinority Leader Mitch McConnell, R-Ky., declined Sunday to endorse hisformer Senate colleague, saying only that whoever is nominated will get athorough vetting. "I'm going to take a look at all the things Chuck hassaid over the years," McConnell said on ABC's This Week. "I'm going towant to see how the hearings go."

Hagel, 66, served two terms inthe Senate, representing Nebraska from 1997 to 2009. He led an Armyinfantry squad in Vietnam in 1968. He was wounded in action there andreceived two Purple Hearts.

Hagel, if approved by the Senate,would succeed Leon Panetta and would inherit a military frayed by morethan a decade of war and facing at least $500 billion in spendingreductions over the next decade. It is also shedding about 100,000soldiers and Marines.

Since his name surfaced as a potentialnominee, Hagel has come under criticism from some supporters of Israeland gay groups for comments he has made.

Hagelonce referred to the "Jewish lobby" in reference to advocates forIsrael who lobbied the Senate. In 1998, he referred to a nominee forambassador in the Clinton administration as "aggressively gay."

Hagelsaid he misspoke about Israel's supporters and recently apologized forthe comment about the gay nominee.Hagel has angered fellow Republicans.He voted to authorize President George W. Bush to use force in the runup to the Iraq War, but he later lamented the way the wars in Iraq andAfghanistan were fought.

Some Republicans, including Arizona Sen.John McCain, said Hagel has been too critical of Israel and too soft onIran and its nuclear program.

Sen. Lindsey Graham, R-S.C., said onCNN that he likes Hagel personally, but he is "out of the mainstream"on foreign policy views, and his nomination would be "antagonistic."

"This is an in-your-face nomination by the president," Graham said. "This is a controversial pick."

Sen.Dick Durbin, D-Ill., the Senate's number two Democrat, noted that Hagelis a Republican, a decorated combat veteran who served in Vietnam, andhas vast foreign policy experience. Speaking on CNN's State of theUnion, Durbin also pointed out that Obama won the presidential election,and is entitled to name his team. "Yes, (Hagel) is a seriouscandidate," Durbin said.

In an interview on NBC's Meet the Press a week ago, Obama praisedHagel as "a patriot. He is somebody who has done extraordinary work bothin the United States Senate, somebody who served this country withvalor in Vietnam. And is somebody who's currently serving on myintelligence advisory board and doing an outstanding job."

In response to criticism from gay groups, Obama noted Hagel's recent apology for his comment about the ambassador nominee.

Hagelwould face immediate decisions on Pentagon issues. The pace of thewithdrawal of troops from Afghanistan - all U.S. forces are scheduled todepart by 2014 - will be at the top of the list. There are about 66,000U.S. troops there now, and commanders would like to keep as many aspossible through next summer, when fighting peaks.