Panameñista Deputy Luis Eduardo Quirós reported that the meeting is scheduled for 4 p.m.
The Panameñistas have concerns about Adames due to his links with former President Ricardo Martinelli.
At least 24 members of the PRD, of the 26 who make up that party's caucus, are supporting Adames, as well as Samir Gozaine as the second vice president.
The PRD and the Panameñista parties signed a legislative alliance last year which, among other things, called for the parties to alternate control of the Assembly. Panameñista Deputy Adolfo Valderrama is the current president of the Assembly. His term expires July 1.