Nandi Senator Samson Cherargei, MPs Nelson Koech, Wilson Kogo and Didmas Barasa are yet to be arraigned at a Bungoma court.
The Bungoma County Criminal Investigations Officer Joseph Ndolo said the four will be charged with preparing to commit a felony.
The four parliamentarians were arrested Thursday morning for allegedly intimidating voters during the ongoing by-election in Kabuchai Constituency in Bungoma County.
The leaders were whisked away to Bungoma Police Station for interrogation shortly after escorting the UDA party candidate Evans Kakai to cast his vote.
They have since denied accusations that they were carrying weapons in their vehicle to cause chaos and disrupt voting.