On September 11, 2012, Islamist militants attacked the US diplomatic compound in Benghazi, killing four, including US Ambassador Chris Stevens.
"The Benghazi thing is going to be very difficult for [Clinton] to dig out of that hole because people want their president to be someone who will defend American missions, diplomatic missions around the world," Paul told WVLK radio on Wednesday as quoted by CNN.
On Tuesday, US State Department Inspector General Steve Linick said US diplomatic security weaknesses continue to put personnel stationed overseas at risk since the Department’s leaders have failed to implement recommendations outlined by a US government accountability review board in the wake of Benghazi.
US Republican lawmakers have repeatedly claimed that the State Department and President Barack Obama did not send military back-up to Benghazi to avoid admitting that the attack was mounted by al-Qaida-backed terrorists.
Then-US Secretary of State Hillary Clinton took responsibility for mistakes made in the aftermath of the attacks, but rejected accusations that the Obama administration had tried to mislead Americans.
On April 12, Hillary Clinton announced that she would seek the Democratic presidential nomination, joining the 2016 US presidential race.
Rand Paul as well several other candidates including Senator Marco Rubio and his fellow Republican Sen. Ted Cruz have also announced their presidential bids.
Sen. Rand Paul, a 52-year-old ophthalmologist and Kentucky lawmaker, is a son of Ron Paul, who ran unsuccessfully for the US presidency in 2012. He advocates tax and military budget cuts, though he recently changed his tune and suggested drastically increasing military spending by 16 percent ahead of seeking the Republican nomination.