This post has been updated.

Senate Minority Leader Mitch McConnell (R-Ky.) said Saturday that there's a chance Republicans will force a cloture vote on former Nebraska senator Chuck Hagel's nomination as secretary of defense. But a successful filibuster is unlikely as several Republicans have said they will not block the nominee. 

"Sen. Hagel did not do a very good job before the Armed Services committee," McConnell told Kentucky reporters. (Hagel struggled in the Senate committee hearing, appearing unprepared for aggressive questions about Iran, Israel and nuclear weapons.) "I think the opposition to him is intensifying. Whether that means he will end up having to achieve 60 votes or 51 is not clear yet." McConnell did not say how he planned to vote.

Democrats have 55 votes in the Senate; they would need five Republicans to break a filibuster. Sen. Thad Cochran (R-Miss.) and Sen. Mike Johanns (R-Neb.) are supporting Hagel. Sen. Roy Blunt (R-Mo.) told MSNBC last week that he was against a filibuster, even though he planned to vote against Hagel in the final vote. Sen. John McCain (R-Ariz.) said Monday that he also opposes a filibuster and will urge his colleagues against mounting one. Sen. Susan Collins (R-Maine) has told reporters that she's "not inclined to support a filibuster." Sen. Lisa Murkowski (R-Alaska) is generally opposed to filibustering Cabinet nominees. “One of the prerogatives of the president is to appoint his Cabinet,” she told the Omaha World-Herald.

A filibuster against Hagel would be unprecedented. A Cabinet nominee has never been defeated by filibuster, although nominees have been voted down by a majority (John Tower was the first in three decades) or pulled over scandal or opposition (Tom Daschle, Bernard Kerik).

Individual Democrats have, in the past, put holds on Cabinet nominees — Sen. Tom Carper (D-Del.) put a hold on President George W. Bush's nominee to head the Environmental Protection Agency*, Stephen Johnson over a dispute involving the the "Clear Skies" initiative, and Sen. Bill Nelson (D-Fla.) put one on Dirk Kempthorne, Bush's nominee for Interior, over offshore drilling. But both nominees were confirmed after cloture votes. (Judicial and non-Cabinet level nominations are another story.)

The White House has expressed confidence that Hagel will be confirmed. The Senate Armed Services Committee, where Democrats have a 14-12 edge, could vote on Hagel's nomination as early as Thursday. A Senate floor vote could happen next week.

* The EPA administrator has "cabinet-status" although the head of EPA is not legally in the president's cabinet.