Dunlap trailed first-round leader Justin Shin by one shot entering Thursday's play but carded the day's low round --- matched only by Australia's Brady Watt --- to take the lead entering Round 3 of the 72-hole, stroke-play competition.
Shin shot a 3-under 67 and sits at 9-under, 131 through two rounds.
Beau Hossler, who matched Dunlap's first- round 65, shot 68 on Thursday to take sole possession of third place.
Contenders in the prestigious event made a move on Day 2. Notable players in the top 10 after two rounds include Watt (5-under, 5th), Bryson Dechambeau (4-under, T6), Peter Williamson (4-under, T6) and Max Homa (3-under, T9).
Given that the Porter Cup famously runs 72 holes with no weekend cut, anything can happen over the final two rounds. Players hoping to make a run with two rounds to play include: U.S. Open participant Gavin Hall (2-under, T14), Cameron Wilson (2-under, T14), Michael Miller (E, T21), Brandon Hagy (1- over, T25).
View all second-round scores from the Porter Cup, using the link below.
The Porter Cup is one of the premiere amateur events in the nation. The winner gets a green blazer, as well as an invitation to the Master of the Amateurs tournament in Melbourne, Australia.