But speaking Sunday at Miharati PCEA Church in Nyandarua, Gachagua defended Kituyi, describing him as the right man to steer the coalition's agenda.
"We are united and have agreed on one candidate to face President William Ruto in 2027. At the secretariat, we decided Dr. Mukhisa Kituyi will be our mouthpiece," he said.
Gachagua acknowledged Malala's concerns but urged him to appreciate the balance between youthful energy and experienced leadership.
"We need someone with experience to guide and mentor the youth leaders driving our agenda. That way we can succeed," he added.
The dispute has been compounded by disagreements over the November Malava Constituency by-election, where both DCP and DAP-Kenya have insisted on fielding their own candidates despite calls for a united front.
Dr. Kituyi, a former UNCTAD Secretary-General and Trade Minister, was unveiled by Kalonzo on September 3.
He is tasked with streamlining opposition communication and rallying support across the country.
While Gachagua maintains the coalition remains intact, Malala's defiance points to early cracks in the quest to forge a united opposition strong enough to challenge President Ruto in 2027.