President Barack Obama could announce former Republican senator Chuck Hagel as his pick for defense secretary as early as Monday, despite senior GOP figures raising questions over the seemingly imminent nomination.

Numerous media outlets cited unnamed White House and congressional aides as confirming that the former Nebraska senator would be named as the replacement for Leon Panetta, with a White House statement expected in the coming days. This would set up a confrontation with Hagel's detractors in the Senate, many from his own party, who believe that he has only been lukewarm towards the US's traditional ally in the Middle East, Israel. One senior Republican said on Sunday that it would be an "in-your-face" nomination by the president.

Hagel has also been criticised for comments he has made over the effectiveness of sanctions in dissuading Iran from pursuing its nuclear programme.

The appointment of Hagel would give Obama credibility regarding his expressed desire for a bipartisan cabinet. Many Republicans, however, are bracing for battle. On Sunday's round of political talk shows, senior GOP figures went on the offensive.

"It is an incredibly controversial choice," the South Carolina senator Lindsey Graham told CNN's State of the Union. "This is an in-your-face nomination by the president to all of us who are supportive of Israel." Hagel has been critical of the influence of pro-Israeli lobbyists in Washington on US foreign policy.

The Senate's top Republican, the minority leader Mitch McConnell, was more reserved in his comments. Speaking on ABC's This Week, McConnell said Hagel "has certainly been outspoken" on foreign policy matters in the past. He added that if the nomination was made, he would want to see if the former Nebraska senator's views "make sense for that particular job".

The likely confirmation battle in the Senate comes after the Obama administration backed down from a similar fight over Susan Rice, the ambassador to the United Nations who had been Obama's first pick to replace Hillary Clinton as secretary of state. Rice withdrew under a barrage of criticism from Republicans, regarding remarks she made in the aftermath of the assault on the US consulate in Benghazi in September that killed the ambassador to Libya, Chris Stevens. The White House could face an equally tough battle over Hagel.

"The administration has a lot of work to do on Hagel. He is in a weaker position now than Rice ever was because Rice would have rallied Democrats behind her," a Senate Democratic aide told Reuters. But Obama has already pressed the case.

"I've served with Chuck Hagel. I know him. He is a patriot. He is somebody who has done extraordinary work both in the United States Senate, somebody who served this country with valour in Vietnam," the president told NBC's Meet the Press last week.