According to a report in The Star Online, Leong was with DAP adviser Lim Kit Siang at a political forum in a Jerantut coffee shop when several disgruntled members confronted him.
Making a scene, they yelled at him before an egg was hurled, hitting Leong squarely on the chest.
The group then proceeded to tear down the Jerantut DAP service centre’s signboard before leaving the venue.
It is believed the members’ unhappiness stemmed from the DAP’s failure to field their favoured candidate, Koh Boon Heng, for the Damak state seat in the country’s last general election, due to a tussle over seats with their coalition partner, PKR, in the then Pakatan Rakyat.
Koh went on to contest as an independent candidate in a four-way battle against MCA’s Lau Lee, PKR’s Jamaluddin Abd Rahim and another independent candidate, Mohd Nor Jaafar.
Lau narrowly edged out Koh by 64 votes, ensuring the seat remained in Barisan Nasional’s hands.