The two politicians with the biggest say over how much Minnesota invests in its highways are far from agreement on whether a state gas tax should be increased for the first time in two decades.

On Tuesday Democratic Congressman Jim Oberstar, the chairman of the House Transportation Committee, strongly urged state leaders to boost the gas tax to make sure Minnesota can provide required matching funds for the millions of dollars in federal highway financing Oberstar could send the state’s way.

On Wednesday, Republican Gov. Tim Pawlenty repeated his opposition to a gas tax hike not only for the 2007 legislative session but for the remaining three years of his term.

“We have some differences with Congressman Oberstar,” Pawlenty said during a conference call with outstate Minnesota reporters.

Pawlenty said the state’s transportation fund will eventually see another $300 million because motor vehicle sales taxes that previously went to the state’s general fund will be dedicated to highway and transit spending. That change came after voters agreed to amend the state Constitution to require the Motor Vehicle Sales Tax to be dedicated to transportation programs.

That’s enough new revenue, according to Pawlenty, who pledged to oppose statewide tax increases during his first four-year term. He didn’t repeat that pledge while seeking re-election last fall, but he isn’t budging on the gas tax.

“I don’t think we need to or should raise the gas tax in Minnesota,” Pawlenty said. “... That would apply going forward as well.”

Oberstar, one of the most powerful members of the U.S. House because of his ability to direct highway funding to various projects and states, strongly disagreed while speaking to a joint hearing of the state House and Senate transportation committees.

Oberstar said more state money is needed to leverage all of the $4.3 billion in federal funds available to Minnesota through 2009.

“If you haven’t got enough money, then raise the user fee,” Oberstar told the state lawmakers.

Minnesota hasn’t increased its 20-cent-per-gallon gas tax since 1988, meaning inflation has severely reduced the buying power of the tax. Since 1988, 45 other states have boosted their gas tax, said Oberstar, and some index the tax to inflation to allow revenue to match rising costs of highway construction.

Blue Earth County Public Works Director Al Forsberg said the state is definitely falling behind in needed road work, both at the state and local levels. State aid to counties is directly tied to the gas tax through a transportation trust fund financed by gas tax and vehicle registration revenues.

“The growth in revenue just hasn’t been there,” Forsberg said. “It’s barely enough to maintain the pavement we have out there.”

That leaves little money for new roads to serve a growing population, he said. And inflationary pressures have been particularly hard on construction costs. At the same time, higher gas prices have prompted drivers to purchase more fuel-efficient vehicles. That’s prompted declines in the amount of gas tax revenue projected by state officials.

In fact, one Minnesota Department of Transportation projection shows less money being available for road construction than previously predicted even after the $300 million from MVST is added, Forsberg said.

He said he doesn’t know if the state will be short of the required matching funds to access available federal highway revenue but believes the state is close to being tapped out.

“I could very easily believe that they’ve gotten to the spot where they couldn’t match the federal funding,” he said.

Pawlenty said Minnesota has options for matching federal funds, saying that other parts of the state budget could be diverted to highway funding if lawmakers really see transportation as a priority. And he made clear he didn’t like Oberstar pushing lawmakers to advance a gas tax hike Pawlenty has promised to veto.

“I was a little concerned with the congressman’s tone,” Pawlenty said.