They are peeved that the National Assembly ignored them and went ahead to pass a separate but related law — the Appropriation Bill — that shares cash among ministries and other agencies.
Their hands are tied in determining what should go into the Division of Revenue Bill, which means they have to approve what is presented to them without variation.
In effect, this is a continuation of the perennial turf war that has defined the relations between the two chambers of Parliament in the past four years.
The dispute on the counties revenue law has grave consequences.
The Senate has only three sittings remaining before its term expires.
If it does not approve the law, counties will be deprived of cash until the next Parliament resumes later in the year.
Yet the counties must operate and deliver services.
Unfortunately, efforts for mediation foundered as the two chambers failed to agree, and that is not an option now.
In the circumstances, the Senate should reconsider its position and approve the Bill.
But the matter should be handled differently in the future by involving both chambers, the National Treasury and the governors in discussing and agreeing on the allocations before the Bill is tabled in the House.