Topeka ? Senators sent a vehicle for funding the state’s comprehensive transportation plan back to the shop Saturday, then test drove another.

An attempt to amend a transportation funding plan into one bill ended after some senators complained that the bill originally dealt with an unrelated subject.

Senators sent the transportation proposal back to the Assessment and Taxation Committee, which met quickly in the Statehouse rotunda to put the funding package into another bill. The panel then endorsed the bill on a show of hands.

The proposal would increase the gasoline tax by 4 cents a gallon on June 1, to 25 cents, and add 2 cents to the diesel fuel tax, also making it 25 cents. In addition, it would increase registration fees for cars and light trucks by $5, to $30.

The plan would provide $57 million a year to the Department of Transportation.

Highway, airport and shortline railroad improvement projects are funded separately from general government services under a 1999 law creating a 10-year, $13.6 billion transportation program.

Many legislators worry that the program won’t have enough money to finance all of the projects the state has promised because lawmakers have diverted money from the plan for general government programs in recent years.

The shortfall in the transportation program could top $1 billion in its remaining seven years.

Lawmakers are trying to cover that gap while also seeking to bridge an estimated $768 million revenue shortfall in the general budget for the next fiscal year.

But some senators were upset with the way the proposal to prop up the transportation program was presented to the Senate and challenged whether the chamber’s rules allowed it to be added to the first bill, which originally dealt with real estate. The Senate first voted that the tactic was acceptable but later reversed itself.

The committee then put the plan into a tax bill that had been stripped of its contents.

Senators now plan to debate their transportation plan Monday.