UDA national vice chairperson Seth Panyako has ditched the party.
He cited his stand against the housing levy proposed by the Kenya Kwanza government and the prevailing high cost of living.
Panyako made the revelation on Saturday during the funeral of former politician Joseph Hamisi in Kakamega.
He said he had informed President William Ruto about the decision on Friday.
"Jana niliongea na rais mwendo was saa moja ikaonekana msimamo ambao nimechukua kupinga mambo ya housing na mambo ya kuongeza gharama ya maisha hainiruhusu kuendelea kuwa kiongozi wa chama ya UDA," he said.
(Yesterday I spoke to the President and it was decided that my stand to object the housing levy and the cost of living did not allow me to continue in the leadership of the UDA party)
"So today, on behalf of my friend (Hamisi), who used to say things as they are, I announce that I have resigned from the UDA leadership position and that I have decamped UDA party," he added.
Panyako said he had decided to become a private citizen.
The unionist said it was wrong that the Kenya Kwanza government had gone back on its promises to hustlers.
On May 14, Panyako criticised Ruto over "betrayal" to Kenyans barely eight months after assuming the top office.
He said Ruto should reconsider his policies, urging him to stay true to the promises he made to the nation during the campaign period.
"We promised Kenyans that we shall lower the cost of doing business, we shall lower the eight per cent VAT on petroleum; today the VAT has been increased while the VAT for helicopters has been removed, how many Kenyans own helicopters?" he asked.
Panyako said no government had attained development through over-taxing its civil servants.
He called for smart measures in the implementation of government programmes.
The outspoken Kenya National Union of Nurses secretary general said the government should implement the housing project through public-private partnerships.
He added that it can also use schemes such as Lapfund and Laptrust instead of imposing the mandatory three per cent housing levy on Kenyans.
Despite government's move to demystify misinformation in the public in relation to the proposed housing levy, the funding has continued to receive backlash from Kenyans.