For the second year, Missouri Gov. Mike Parson has proposed an historic and controversial shift in how highways are funded.

His idea, approved by the legislature last year and recommended again this year, allocates for highways a small piece of "General Revenue" that finances the bulk of non-highway functions of state government including health, welfare and education.

This is an historic shift.

For decades, state highways have been financed by the taxes and fees generated from highway users such as gas taxes, along with matching federal transportation funds.

That highway revenue is placed in a constitutionally protected "State Road Fund" under the total control of the independent Highways and Transportation Commission.

In contrast, the legislature controls use of General Revenue, subject to approval or veto by the governor.

There are exceptions for "earmarked" taxes that, by law, must be spent on specific programs. For example, much of the state's gambling tax revenue is dedicated to education.

A few agencies are completely free from appropriated General Revenue.

The Conservation Department doesn't get a penny of General Revenue. Instead, it's financed by hunting and fishing fees along with a sales tax earmarked for the department.

The Transportation Department is appropriated a very small bit of General Revenue, but mostly for non-highway purposes such as aviation, rail and public transportation.

The governor's proposal to use $50 million of General Revenue to supplement the highway user-fee system for local road projects has raised concerns by a few legislators.

Some complain it's a "rob Peter to pay Paul" approach by diverting General Revenue money from programs like education and health care.

Another issue is the degree to which the governor's approach moves selected highway projects into the political arena by using General Revenue that requires approval by the legislature and governor.

Last year's appropriation even gave Parson's Economic Development Department a voice in the project selections.

That effectively handed the governor bragging rights about the projects.

The Transportation Department's website announcement even linked to the governor's office for the list of approved projects.

Bragging rights by partisan officials would not be possible for projects financed by State Road Fund monies that are under the total control of the Highways and Transportation Commission.

One downside of Parson's approach was demonstrated when a newspaper story reported that a fellow Republican -- former Sen. Jay Wasson, R-Christian County -- sought funding for a project, which he ultimately got.

There was no evidence of political favoritism. But involvement of the Republican administration in awarding a state-funded project sought by a former Republican official raised questions.

In the governor's defense, State Road Fund taxes and fees simply have not kept up with the rising costs to adequately maintain highways and to meet the growing volume of traffic.

For years, the Transportation Department has warned it does not have enough money to maintain the state highway system.

Repeated concerns have been voiced that a deteriorating highway system hinders local business development and recruitment of businesses from other states.

But Missouri voters have not been receptive.

In 2014, state voters decisively rejected a ten-cent-per gallon motor fuel tax increase. In 1970 and 1992 voters decisively rejected toll roads.

In 2012, the Transportation Department director suggested tolls did not require voter approval. But the idea met with stiff legislative opposition.

One Republican senator recently told me the highway infrastructure is so horrid that it warrants General Revenue funding.

An alternative to this quagmire has been sponsored this year by Sen. Doug Libla, R-Poplar Bluff.

His bill would increase the motor fuel tax by just two pennies per gallon.

While not enough to fully resolve the highway funding problems, it's small enough to avoid requiring voter approval.

Of course, in an election year the prospects of any kind of tax increase without voter approval clearing the legislature would appear to be slim.

Even if passed by the legislature, it would be subject to veto by a governor seeking election to a full four-year term.