(CNN) -- U.N. Ambassador Susan Rice made a second trip to Capitol Hill on Wednesday to answer questions from Republican senators about the September 11 attack on a U.S. diplomatic mission in Libya that killed Ambassador Christopher Stevens and three other Americans.

Rice, who is believed to be President Barack Obama's choice to replace Hillary Clinton as secretary of state, triggered controversy with her appearance on television talk shows in the days after the Benghazi attack to explain what was known about it.

She conveyed the view that the armed assault was spontaneous and fueled by an anti-Islam video produced in the United States that had already sparked a notable protest in Egypt. U.S. officials have since described it as a terror attack aimed at American interests.

Here are five questions around Rice's involvement in the controversy.

Q: Why is Rice the focal point in the Benghazi attack?

A: Rice was the only official to speak publicly on behalf of the Obama administration in the days following the attack and made several claims that turned out to be wrong. The primary complaint from Republicans is that Rice's remarks were centered on anger over the anti-Islam film, "Innocence of Muslims," when there was classified intelligence available suggesting a possible al Qaeda link.

Republicans feel that the administration misled the American people before the presidential election, won by Barack Obama, because an al Qaeda attack countered the narrative that Obama's policies, in Rice's words, had "decimated" al Qaeda. For Republican critics, Rice illustrates their problems with how the Obama administration has responded to the Benghazi attack and its fallout.

Q: What are Republican problems with her possible nomination as secretary of state?

A: Most opposition to Rice as a candidate to replace Clinton centers around her role in the Benghazi affair. Sen. Lindsay Graham, who has been supportive of Obama's nominees for the Surpreme Court, says he does not feel comfortable with someone who, in his view, was involved in using misinformation as a Cabinet-level official. Other Republicans argue that Rice is not independent enough to be America's top diplomat. They see her as someone who blindly follows Obama and puts politics over national security. In a dig at Rice, Sen. Bob Corker, who is on the Senate Foreign Relations Committee, said Rice would be a better fit for chairman of the Democratic National Committee than secretary of state.

Q: How much of the GOP's questioning of Rice is politically motivated?

A: To some extent, the harsh treatment of Rice is motivated by politics. Republicans believe the president's handling of the aftermath of the Benghazi attack shows a lack of leadership and tried to make that a campaign issue. Ironically, some are frustrated that Obama's challenger, Mitt Romney, did not take enough advantage of this in the presidential campaign.

Q: Are there other issues besides political ones?

A: For some senators like John McCain, this is personal. Christopher Stevens was a good friend of McCain, which is why he is working hard to avenge his death. Others have voiced questions about whether Rice is the best choice for the job -- she is a tough talker who some might see as too blunt to be secretary of state. However, most Republican senators have said their criticism centers around Rice's role in the Benghazi attack.

Q: Are there others they would rather see Obama nominate to replace Clinton?

A: McCain and several other senators have said that Sen. John Kerry, D-Massachusetts, would make an excellent choice. Kerry is another top contender for the position who has made no secret of the fact he would like the job. After meeting with Rice on Wednesday, Republican Sen. Susan Collins of Maine said, "I think John Kerry would be an excellent appointment and would be easily confirmed by his colleagues."