By Carlo Muñoz - 12/23/12 06:35 PM EST
Sen. Joe Lieberman (I-Conn.) added his voice to the growing chorus of opposition from Congress against the White House's presumptive nominee to replace Defense Secretary Leon Panetta.
During an appearance Sunday on CNN's “State of the Union,” Lieberman expressed doubts on former Sen. Chuck Hagel's (R-Neb.) ability to secure Congress's blessing during a possible confirmation hearing before the Senate Armed Services Committee.
Lieberman said his main concern was focused on "some very outlying votes" -- particularly on the issue of Iran's nuclear enrichment program, Hagel cast during his time in the Senate.
The former Nebraska senator’s vote against extending sanctions on Iran has drawn intense bipartisan fire from allies of Israel. Hagel has also come under scrutiny for his criticism of pro-Israel lobbying efforts in Washington, particularly on Iran, and most recently was forced to publicly apologize for comments perceived by some to be anti-gay.
While Hagel's votes won't necessarily doom his chances at confirmation, Lieberman did say those votes would prompt some "serious questions" over the former senator's stances on key national security and defense issues.
"I served with Chuck Hagel, I worked with him on some things," Lieberman told CNN, "but if I were in the Senate and on the Armed Service Committee and he was nominated, I would have some really serious questions."
When asked how Hagel would likely respond under such questioning and how committee members would react to his responses, Lieberman replied: "I don't know how it would end but there are reasonable questions to ask and that Chuck Hagel will have to answer."
Hagel, who currently serves as the president of the Atlantic Council, has undergone the White House's vetting process for the top job at the Department of Defense (DOD) and is awaiting President Obama's final approval for the Pentagon nomination.
Hagel, former DOD policy chief Michele Flournoy and current Deputy Defense Secretary Ashton Carter were the top three finalists to be Panetta's successor at DOD.
Hagel was also rumored to be at the top on Sen. John McCain's (R-Ariz) list of defense chiefs during his failed presidential bid in 2008.
He is likely to face sharp questioning from GOP senators, however, if he is tapped for the Defense post.
“I want to listen to what he has to say,” Sen. Graham told reporters last Tuesday. “He has a stellar military record, but I think these comments disturb a lot of people and he’ll have to answer those questions. I think this hearing will really matter.”