Retired President Uhuru Kenyatta is selfish and pursuing a dangerous political line, his cousin Kung'u Muigai has said.
Mr Muigai accused Mr Kenyatta of being too temperamental and condescending.
Speaking on Muoroto TV on Wednesday, Mr Muigai urged Mr Kenyatta to quit politics and work to unite Mt Kenya.
"He (Uhuru) was handed a united Gikuyu, Embu, Meru Association (Gema) in 2013 when he was elected president but he left Gema more divided in 2022," Mr Muigai said.
Mr Muigai said the former president should not complain of being insulted.
On 27 March 2023, a gang raided Mr Kenyatta's Northlands farm, stole sheep, cut down trees and divided part of the 50,000 acres into small plots where they erected makeshift structures.
The raids and destruction of property followed a warning from National Assembly Majority Leader Kimani Ichung'wa, who believed Mr Kenyatta was supporting anti-government protests led by Azimio la Umoja leader Raila Odinga.
"Even those (pieces) of land you own, we will raid them... so that those without land can have a share. Don't lie to yourself that ordinary people are the ones who will lose property in the ongoing mass anti-government protests. You too will pay the price if you continue to instigate violence and bloodshed in this country," Ichung'wa said.
He added: "And this is my message to none other than Uhuru Kenyatta, the sponsor, the sole sponsor... the sole financier of Azimio and the mercenary that is Mr Odinga.
Mr Muigai says Mr Kenyatta is using the raid on his farm as an excuse to stay in active politics.
"He should be working for Gema unity instead," said Mr Muigai.
On 22 May, Mr Kenyatta convened the Jubilee Party's controversial National Delegates Conference (NDC), where he complained of being insulted.
Mr Muigai now wants his cousin to realise that it is only in Mt Kenya that politicians fight.
"We embraced you in good faith where former Internal Security Minister John Michuki, on behalf of the third President of Kenya, Mr Mwai Kibaki, endorsed you as the kingpin of Mt Kenya. You should reciprocate and realise that your time is up," he said.
Last year, Mr Muigai, a key ally of President William Ruto, led a faction of Agíkúyú elders to install Attorney General Justin Muturi as spokesman for the Mt Kenya region. He said Mr Kenyatta's stay in active politics was causing unnecessary confusion.
"Those who know how politics works cannot follow Mr Kenyatta in Mt Kenya politics. Follow him to lead you where? He can only lead you to his home compound," he said.
Mr Muigai, however, did not name who should succeed Mr Kenyatta as Mt Kenya's kingpin.
While acknowledging that Deputy President Rigathi Gachagua is the most senior politician from the region, he urged Mr Kenyatta to call a stakeholders' meeting to consult on who should succeed him.
"He should call stakeholders from Mt Kenya to choose the next king. We have given him the instruments of power and it is time to give them to someone else. We should have an open consultative way of choosing our next kingpin," he said.
He said that "Mr Gachagua should stop dwelling too much on how others wronged him even as we ask Mr Kenyatta to stop being selfish and retire from politics".