For one thing, Senate rejections of Cabinet nominations are rare. It hasn't happened since March 1989, when President George H.W. Bush's nomination of former Sen. John Tower, R-Texas, for the top Pentagon job was killed 53-47. Tower faced allegations of private misconduct.
One week ago, Sen. John Kerry, D-Mass., drew bipartisan praise at his hearing to be secretary of state. He was later confirmed 94-3.
If Hagel prevails, it will be by a much slimmer margin.
But the numbers don't say everything.
When a nomination becomes toxic, it is often withdrawn well before a vote.
Obama backed away from New Mexico Gov. Bill Richardson as commerce secretary because of an investigation — later dropped — into his business dealings. Richardson had been Clinton's U.N. ambassador and energy secretary.
Obama also withdrew nominations of former Senate Democratic Leader Tom Daschle to be health and human services secretary and Sen. Judd Gregg, R-N.H., to be commerce secretary. Daschle was embroiled in an income tax dispute, and Gregg said he disagreed with Obama on stimulus legislation and other policies.
Right now, Hagel's nomination seems far from being in such peril.
The nominee rejected GOP charges he was insufficiently supportive of Israel, soft on Iran and too eager to cut defense spending. Sen. James Inhofe, R-Okla., told him his views were "deeply troubling and out of the mainstream."
Then Warner told Hagel: "You're on your own. Good luck."