Verplank shot a 71, to share the 54-hole lead with Ames at 13-under 203.
The main goal this week is for players to move into the top 125 on the money list to keep their tour cards for next year.
Tag Ridings is one of those who need to win this week to keep their cards. He posted a 71 in the third round and is tied for third at 12-under 204 with Mathew Goggin (69), Justin Leonard (70), Jeffrey Overton (69) and Tim Petrovic (68). Overton is 117th on the money list.
Eight different players took a piece of the lead during Saturday's round.