WASHINGTON (February 4, 2013)--Senate Minority Leader Mitch McConnell is raising the possibility of a filibuster to block confirmation of President Barack Obama's nomination of Chuck Hagel to be the next defense secretary.

McConnell told Kentucky TV station CN2 that it’s "not clear yet" whether Hagel will need a simple majority of 51 votes or 60 votes to secure Senate confirmation.

McConnell declined to say whether he backs the president's pick of the former two-term Republican senator, but did say opposition was intensifying after Hagel seemed unprepared at his confirmation hearing before the Armed Services Committee last week.

More than a dozen Democrats and two Republicans have announced their support for Hagel, including Nebraska GOP Sen. Mike Johanns this past weekend.

About a dozen Republicans have said they will vote against Hagel.