Hemedti and Burhan have both excluded the idea of negotiating with each other in public comments since the fighting began.
An aide to Hemedti did not respond to questions from Reuters about whether he was ready to negotiate or hold peace talks.
"What are they going to talk about that wasn't on the table before the conflict started?"
said the diplomat, adding that neither side could win a decisive military victory or control of all Sudan's territory.
The RSF, which has bases across Sudan, has meanwhile depicted the army as "extremists", an apparent reference to the influence Hemedti says Islamists wield in the military.