Nominees who prove toxic are often withdrawn before they get a vote. When controversial nominees get that vote, they rarely lose, though the new president often has to spend valuable political capital winning approval. In 2009, Attorney General Eric Holder weathered a stormy confirmation hearing – and Republican-imposed delays – and was confirmed with 75 votes.

Republicans see Rice through a broad lens: They want more answers on the Libya incident – and view it as a way of scoring points against Obama – and criticizing Rice is an attention-getting way of accomplishing that goal.

“We will do whatever’s necessary to block the nomination that’s within our power as far as Susan Rice is concerned,” McCain told a news conference. He and other Republicans want a special committee to investigate the Libya incident.

Sen. James Inhofe, R-Okla., a senior Foreign Relations Committee member, went further, saying Rice’s problems go beyond Libya.

“Rice has been the Obama administration’s point person in pursuing liberal causes that threaten U.S. sovereignty,” he said. “She has also not been an effective diplomat or manager at the U.N.”

The nomination first would be considered by the Senate Foreign Relations Committee, now chaired by Sen. John Kerry, D-Mass. Kerry has been mentioned for State as well as Defense.

The committee’s top Republican is slated to be Sen. Bob Corker of Tennessee, known for cooperating with Democrats.

Wednesday, Corker would not go as far as some Republicans, but he was puzzled why Rice did not know more about the incident.

“It’s a very big problem,” he said. “We all rely on people in these positions to be transparent and honest.”

“How could we, knowing that our intelligence officials in Libya in real time . . . were letting our folks know back here that this was a terrorist attack – it’s beyond me that we would be out publicly talking about the event in that way," he said.

But unlike others, Corker would not say whether Rice could be confirmed. “You have to give someone a full hearing,” Corker said.

Democrats were more sympathetic.

“She’s qualified to be secretary of state,” said Senate Armed Services Committee Chairman Carl Levin, D-Mich. “She may have had bad information.”

Levin urged considering the whole of Rice’s resume, and to wait to hear her side of what happened regarding Libya.