As Democratic presidential candidate Hillary Clinton prepares to testify before the House Select Committee on Benghazi, here's a breakdown of what happened from the attack on Sept. 12, 2011 to the current political controversy. (Sarah Parnass/The Washington Post)

Come Thursday morning, only seven Republicans will get a chance to grill former secretary of state Hillary Rodham Clinton about the 2012 terrorist attacks in Benghazi. The rest of Washington’s Republicans can only share advice: Please, please, don’t mess this up.

“Find out what happened,” said Sen. John McCain (R-Ariz.), one of the first Republicans to demand a special investigation. “There’ve been self-inflicted wounds, but I don’t think they change the fundamental facts.”

Those wounds have come to define the Select Committee on Benghazi, which — as Democrats do not tire of pointing out — is in its 17th month investigating the deaths of four Americans, including U.S. Ambassador J. Christopher Stevens, at a diplomatic compound and CIA annex in Benghazi, Libya.

Rep. Trey Gowdy (R-S.C.), the committee’s chairman, has been dragged into an increasingly bitter argument with the committee’s Democrats. But now, even Republicans are offering guidance — and expressing anxiety — about how the committee should proceed on Thursday to avoid an overreach that could help the Democratic presidential hopeful and backfire on the GOP.

The case of nerves began in early October with House Majority Leader Kevin McCarthy’s petard-hoisting candor about how Clinton’s “numbers are dropping” thanks to the committee — a seeming acknowledgment of political intent that Democrats seized on to discredit the committee’s work.

“Listen, there was a really misinformed statement that was made,” said Sen. Richard Burr (R-N.C.), chairman of the Senate Intelligence Committee. “But if you look at the work of the committee, it’s never been targeted at her personally or at her e-mails. It’s always been about four Americans who died.”

That point has been obscured in the wake of McCarthy’s gaffe, capitalized on by Clinton allies who could scarcely believe their luck. In an NBC News-Wall Street Journal poll released Tuesday, just 29 percent of voters called the committee “fair and impartial.” Thirty-six percent called it “unfair” and unduly partisan.

Republicans outside of the committee are frustrated with its recent results. They are also nervous about a repeat of the Planned Parenthood hearings, which many of them believe amounted to a lost chance to score points against the abortion provider over controversial videos that have captivated conservatives.

Even Clinton allies cite the Planned Parenthood hearings as a model for how the secretary could navigate the Benghazi hearing Thursday.

“We’ve heard from many members of the House who are embarrassed that its committees and oversight have become a joke under Speaker [John] Boehner,” said Tom Fitton, president of the conservative Judicial Watch, who argued that watchdog groups such as his have gotten more vital information than Gowdy’s Benghazi committee.

In recent interviews, Gowdy has lashed out at colleagues for undermining him — and media for parroting his critics.

“It’s not lost on me that the uptick in criticism is [happening in] the two weeks before she’s coming,” Gowdy told Politico. “I don’t think that that is a coincidence; it’s an attempt to marginalize and impugn the credibility of the panel that’s going to be asking her questions.”

Gowdy’s Democratic critics appear to have rattled him, most recently after the committee’s majority mistakenly claimed that Clinton’s e-mail outed a CIA contact. Gowdy cried foul in a public letter to Rep. Elijah E. Cummings (Md.), the ranking Democrat on Benghazi panel. “I am envious of your staff’s ability to get information from this administration in less than 45 minutes on a weekend,” he added.

Democrats were not amused.

“Those of us who are concerned about Benghazi, and we ought to be, are concerned about making our embassies safer,” said Sen. Timothy M. Kaine (D-Va.). “A hearing like this — it’s not really about the issue at all. The entire discussion about Benghazi, since I got here in January 2013, has been focused on blame.”

On and off the committee, Republicans were hopeful that they could investigate the errors of Clinton’s State Department without the appearance of politics. “It’s not our fault that she was secretary of state,” Rep. Lynn A. Westmoreland (R-Ga.), a committee member, said Tuesday morning on CNN. “This isn’t about Hillary. She just happened to be there as secretary of state when this occurred. If John Kerry had been there, we’d be looking at John Kerry.”

Not every committee member has evaded the politics. In an appearance Sunday on NBC’s “Meet the Press,” Rep. Mike Pompeo (R-Kan.) suggested that Clinton got “most” of her foreign intelligence from political ally Sidney Blumenthal, an attack line that wasn’t true.

Sen. Lindsey O. Graham (R-S.C.) argued in an interview with The Washington Post that Blumenthal was relevant only as an example of who did and did not have access to the secretary at key moments.

“I find it really odd that Sidney could e-mail her about Libya and the ambassador to Libya couldn’t,” said Graham, who is running for president. “Don’t make speeches — ask questions. That would be my advice to the committee. Try to find out what happened, in a coherent fashion, before and after the attack. Put facts on the board: How many requests for additional security were made, how many were denied, and why they were denied? How could the secretary of defense know about deterioration in Benghazi but not the secretary of state?”

Sen. Susan Collins (R-Maine), who was the ranking Republican on the Homeland Security and Governmental Affairs Committee when it produced one of the first and quickest Benghazi reports, suggested that the committee can get what it needs if it simply focuses on the decisions not to reinforce security at the American diplomatic outpost.

“A lot of legitimate questions should be asked about the requests for increased security,” Collins said. “One of the patterns that we found, dating back to the [1998] attacks in Nairobi, that there had been repeated requests for beefing that up and they had been ignored.”

Sen. Rand Paul (R-Ky.), a GOP White House hopeful who has said that the Benghazi disaster “disqualifies” Clinton from the presidency, said that the witness needs to explain why so many nervous cables from the ground were ignored. Sen. Ron Johnson (R-Wis.), now the chairman of the Senate Homeland Security Committee, hoped for the same thing.

“We’ve seen the cables asking for additional security measures,” he said. “Where did those stop? Who saw those? We’ve never gotten to the bottom of that.”

Johnson’s view of a Clinton interrogation is unique. In 2013, both he and Paul used perches on the Senate Foreign Relations Committee to ask why the State Department initially suggested that the attack on the U.S. diplomatic compound was spontaneous, a protest gone wrong. As Johnson prodded Clinton, she accused him of being frivolous.

“What difference at this point does it make?” asked an agitated Clinton. “It is our job to figure out what happened and do everything we can to prevent it from ever happening again.”

At the time, Clinton was seen as the winner of the exchange. But in the years since, “what difference does it make” has turned into a bumper sticker — a way for conservatives to say that Clinton was callous when asked about the biggest failure of her tenure.

“My guess is that she regrets saying it,” Johnson said wryly, raising his arms to imitate how Clinton answered him. “Half the pictures I see of her, she’s in that green jumpsuit with the black glasses. She was glaring at me at that moment.”