A governor who may soon run for president on the Republican ticket can’t allow himself to get anywhere near a tax increase — even for road projects — so Scott Walker wants to put Wisconsin’s transportation budget on the credit card.

That would be a mistake — one that even members of Walker’s own party recognize. There are other alternatives that make more sense, including a system that would assess fees based on miles driven, tolling or, yes, even a hike in the gas tax.

Instead, Walker wants to use $1.3 billion in borrowing to pay for transportation projects over the next two years. In total, state borrowing would fall because the governor also is recommending delaying construction of new buildings that have already gotten the initial OK. Some of those are for the University of Wisconsin System.

Delaying some of the projects probably makes sense. We wonder, for example, if the UW System has adequately considered the impact of demographics and the effects of online learning on its plans. The demographics factor applies to some road projects, as well.

But we question whether increased bonding for transportation is the best approach when other, better ideas are available. Debt service is an increasing cost in the state transportation budget — eating up about 19 percent of state money that flows into the transportation fund. There is no free lunch.

The current system doesn’t work. The gas tax, which has long funded road building and maintenance, is no longer adequate as vehicles become more fuel-efficient. So a new system is needed, but not pulling out the state version of a Visa card. The state needs a permanent answer.

And here’s the thing:  Walker has a way out. He could adopt the recommendations of his own transportation secretary, Mark Gottlieb, who recommended in November that taxes and fees rise by $751 million over two years. He proposed increasing the gas tax by changing how it is calculated, imposing a new 2.5-percent fee on vehicle purchases, and placing a new fee on hybrid and electric vehicles.

But that plan is problematic for a politically ambitious governor.