"I seek guidance on how to remove and hence replace a commissioner of the PSC…your urgent consideration of this matter will be highly appreciated," the letter signed by Mr Mohamed read in part.
Close to 10 MPs from the Coast region have already sided with Ruto and have been seen attending the DP's events at the coast.
Other leaders within the party who have been irked by the apparent shift of loyalty in the region include deputy party leader and Mombasa Governor Hassan Joho, who himself has declared intentions to contest for the top seat in 2022.
Ms Jumwa is among MPs who skipped the parliamentary group meeting chaired by the former Prime Minister in Mombasa earlier in the week.
ODM Secretary-General Edwin Sifuna noted that the alleged rebel MPs would be summoned and disciplinary measures taken against them following the no-show.
The Daily Nation reports that the ODM camp plans to take stern action against the non-compliant MPs through similar demotions from the parliamentary committees they sit in.