The caucus of the governing Panameñista party is seeking an agreement with the Democratic Revolutionary Party (PRD), with which it has an alliance in the chamber. The Panameñistas are reluctant to support a candidate unless the PRD announces its candidate two days before the July 1 election.
The Panameñistas also have to name a vice presidential candidate.
Panameñista Deputy Luis Eduardo Quirós said the PRD should not wait until the end of the month to make the announcement.
But PRD leaders have called on the Panameñistas to support any candidate they put forward.
"Our decision must be respected," said PRD Deputy Iván Picota.
However, the PRD caucus is concerned that the Panameñistas will seek an alliance with the Democratic Change (CD) party to shut the PRD out of power.