Americans have much to grumble about in the fallout from the deadly attacks on U.S. compounds in Benghazi, Libya, in 2012. Majorities in a new Washington Post-ABC News poll disapprove of the way Hillary Rodham Clinton has handled questions about the attacks and her conduct using a personal e-mail server while secretary of state.

But a nearly equal majority identify the Republican-led investigation into the events as a politically motivated attempt to damage the former secretary of state rather than an effort to raise legitimate concerns.

[Read full poll results]

Clinton testifies Thursday before the House committee investigating Benghazi, a long-planned showdown between the Democratic presidential front-runner and investigators whom her supporters accuse of conducting a partisan witch-hunt. Clinton is expected to repeat her long-standing claim that she had nothing to do with State Department decisions that might have averted or blunted the attacks that killed four Americans, including the sitting U.S. ambassador to Libya.

A Clinton campaign aide said Wednesday that diplomats must continue to work in dangerous places and take risks, and that a retrenchment would draw the wrong lessons from Benghazi.

Clinton will talk about Ambassador J. Christopher Stevens, a rising star whom Clinton knew and had sworn in for his post, and his embrace of the foreign policy concept of “expeditionary diplomacy,” said the aide, who spoke on the condition of anonymity to preview some of Clinton’s testimony.

In the new Post-ABC poll, 36 percent approve of Clinton’s handling of questions about her e-mails while 57 percent disapprove. The result is nearly identical on Benghazi, with 35 percent approving and 54 percent disapproving. There has been little change in the public’s negative assessment of Clinton since May — 55-57 percent have disapproved of her answers to questions about her personal e-mail server, and 50-54 percent disapprove of her answers on Benghazi.

Clinton exclusive use of a private e-mail system for her government work came to light because of the committee’s work. The FBI is investigating whether classified information was compromised.

Critics of the House Select Committee on Benghazi were emboldened by House Majority Leader Kevin McCarthy’s suggestion last month that the panel was created with an eye toward damaging Clinton’s poll numbers, an accusation Chairman Trey Gowdy (R-S.C.) has denied.

Clinton and her allies pounced immediately, pointing to McCarthy’s gaffe as evidence of what they claim was a plan all along to use the power of the congressional investigative committee to search for damaging information about Clinton and call her to testify in what could be uncomfortable circumstances. The deaths marred Clinton’s tenure as secretary of state, one of her main qualifications for the White House.

But the poll results suggest that McCarthy’s statement did not change Americans’ views on Clinton’s actions, even though they are skeptical of Republicans’ motives. Fifty-three percent in the new poll said Republicans are mainly trying to damage Clinton with the hearing, while 35 percent say they are mainly raising legitimate concerns.

That is a more negative picture than found in a related question from more than two years ago. In May 2013, the public divided nearly equally on whether House Republicans were raising legitimate concerns (44 percent) or whether their inquiries merely offered members an opportunity for political grandstanding (45 percent).

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)

Both Clinton’s e-mails and the committee’s motives elicit sharp partisan differences. More than 8 in 10 Republicans disapprove of the way Clinton is handling questions about Benghazi and her dealings with her private e-mail account. A smaller majority of Democrats, about 6 in 10, approve of Clinton’s handling of questions on each issue, with about 3 in 10 disapproving. Independents are more negative, with 55 percent disapproving of Clinton’s answers on Benghazi and 60 percent disapproving of her responses about personal e-mail.

Attitudes are a mirror image when rating Republicans on Benghazi. More than 8 in 10 Democrats say the investigation is aimed at damaging Clinton, while 65 percent of Republicans say it’s raising legitimate concerns; 31 percent say it is in part politically motivated (mainly or “both” raising legitimate issues and aimed at Clinton together). Independents are downbeat again — by 53 to 35 percent, more say Republican investigators are focused on hurting Clinton.

The Post-ABC poll was conducted Oct. 15-18 among a random national sample of 1,001 adults, including land-line and cellphone respondents. Full results have a margin of sampling error of plus or minus 3.5 percentage points.

Scott Clement contributed to this report.