Democratic presidential front-runner Hillary Clinton has been compelled to turn over the private email server that she used as the Obama administration’s secretary of state, her campaign revealed Tuesday.

The handover represents a reversal of her previous refusal to surrender the server to federal investigators probing whether its use included the improper storing of unsecured classified information.

Previously, Clinton had insisted that she had fulfilled her responsibilities by turning over approximately one half of the 62,320 email messages she sent or received as secretary of state. The rest, she and her lawyers claimed, concerned private matters and not official business.

Possession of the server could allow the FBI to recover deleted emails that Clinton claimed were private.

The sudden reversal came on the same day that the inspector general for the intelligence community, I. Charles McCullough III, sent a letter to leaders of a congressional oversight committee indicating that at least some of the emails received via the server, which was kept at Clinton’s home in Chappaqua, New York, contained top secret information.

McCullough’s office reviewed a sample of 40 Clinton emails and reportedly found that at least four of them contained classified information, while two more included top secret material. Most of the classified information originated with the CIA.

A State Department spokesman said that the emails had not been designated as top secret at the time they were sent and have previously circulated on unsecured department servers.

Clinton’s campaign spokesman refused to say whether or not the FBI had ordered the handover of the server, the Washington Post reported.

Turned over to the FBI along with the server was a thumb drive containing copies of the emails that Clinton previously designated as official and gave to the State Department last December. The State Department had previously refused to give the same emails to the intelligence inspector general’s office.

In his letter to congressional leaders, McCullough reported that he found two emails from a separate group of 296 that contained classified material related to the September 11, 2012 attacks on the US consulate and a secret CIA station in the eastern Libyan city of Benghazi. The US ambassador to Libya and three other Americans were killed in these attacks, which were staged by an Islamist militia.

Republican congressional leaders have accused Clinton of lax security policies and an alleged cover-up of the facts surrounding the Benghazi attacks, a ploy designed to derail her presidential campaign by branding both Clinton and the Obama administration generally as “soft on terrorism.”

Congressional investigations of the Benghazi events have carefully steered clear of the real roots of the attacks, which lay in Washington’s policy—backed by both major parties—of arming and supporting Al Qaeda-linked Islamist militias in the US-orchestrated wars for regime change in both Libya and Syria.

Republicans have also preferred to concentrate on the trumped-up allegations concerning security and cover-up over Benghazi rather than pursue the ample indications that the activities of the Clinton Foundation and the exceedingly lucrative speaking engagements of her husband, former US president Bill Clinton, likely involved Hillary Clinton in influence peddling. The issue of self-enrichment through political office and connections is a sensitive topic for both Democrats and Republicans.

Clinton’s about-face on surrendering her server to the FBI will undoubtedly prolong and deepen the controversy surrounding her use of private email as secretary of state. This came as polls showed her trailing Vermont Senator Bernie Sanders by a margin of 44 percent to 37 percent in the early primary state of New Hampshire.

The latest polls have also shown that nearly six out of ten US voters believe Clinton is neither honest nor trustworthy, roughly the same rating the polls give for the billionaire real estate developer and reality TV host Donald Trump, who has been leading the pack of Republican presidential hopefuls.