It wasn't primarily her views on foreign policy; Rice and McCain actually aren't that far apart on many issues. (They both pressed for U.S. intervention in Libya's civil war, for example.)
Officially, the GOP crusade against Rice was over her statements on what Washington calls simply "Benghazi," the Sept. 11 attack on a U.S. consulate that left four Americans dead. But the controversy over Rice's recitation of White House talking points on Sunday television shows was flimsy at best. The real questions about Benghazi are on State Department security practices (Hillary Rodham Clinton's department) and intelligence community analyses (James Clapper's purview), not Rice's spokesmanship.
And by last week, Rice and others had shown that she wasn't the one who wrote the talking points; she merely voiced them.
No matter, Republican senators said; there were other problems they needed to look into. GOP aides drew up dossiers on Rice's record on Africa policy as an assistant secretary of State in the Clinton administration. GOP senators charged that she behaved too much like a political operative, an attribute that never disqualified a secretary of State before. (James A. Baker III, one of the best, was a campaign manager before he became a statesman.)
So, if it wasn't just Benghazi, and it wasn't Rice's record, what was it that had Senate Republicans so riled up?
A big factor was something that would seem to be unrelated: the "fiscal cliff." Senate Republicans may soon face a vote over raising tax rates on upper-income taxpayers, a compromise that will be anathema to their most conservative supporters. A long list of old-right leaders has already issued a letter warning that any Republican who votes for higher taxes will face a primary challenge from the right.
Tennessee Sen. Bob Corker, one of the few GOP senators who has said he might support a tax hike, said Thursday that the fiscal-cliff battle made this the wrong time for a controversial nomination. "To add this to the equation probably would have been more than any of us could bear," Corker told the Wall Street Journal.
A Republican Senate aide spelled out the situation for me more clearly, on condition he not be identified. "Voting for higher taxes is a tough vote," he said. "Opposing Susan Rice is a way to score points, even though it's a sideshow."
Another factor in Rice's downfall may have been old animosities. Things got personal during the 2008 campaign, and Rice acted as Obama's designated brawler on foreign policy issues. That's something McCain is unlikely to have forgotten — or forgiven.
During the campaign, Rice not only attacked McCain's policies, she questioned his judgment, his temperament and even his courage, ridiculing him for "strolling around the market in a flak jacket" during a visit to Iraq.
During a mini-crisis over Russian intervention in neighboring Georgia, Rice offered this: "Barack Obama, the [Bush] administration and the NATO allies took a measured, reasoned approach…. John McCain shot from the hip [with] a very aggressive, belligerent statement. He may or may not have complicated the situation."
I don't think those old grudges were the key factor in McCain's opposition. But they didn't help either.
Rice did her president a favor by bowing out. Obama and his aides know that their ability to do big things in his second term will erode over time; as Rice noted, energy spent on a bitter confirmation battle would be energy robbed from other priorities such as immigration reform.
But the fight made clear that nothing will be easy for the president during the next four years, despite his thumping 332 electoral votes. Republicans are looking for issues on which to bedevil Obama, including other nominations. Just because Rice withdrew is no guarantee that the president's other choices will get a free pass.
Already, the potential nomination of former Nebraska Sen. Chuck Hagel as defense secretary is meeting resistance. Hagel's a Republican, but conservatives consider him an apostate (he endorsed Democratic Senate candidates in Pennsylvania and Nebraska; even worse, both lost) and some pro-Israel groups worry that he's soft on Iran.
And Republicans have said they won't be happy if Obama nominates Jacob Lew, his White House chief of staff, as secretary of the Treasury.
About Susan Rice, the GOP aide insisted that "it was nothing personal." He didn't say — but could have — that it was, instead, strictly politics.