ST. PAUL  — A big new coalition of businesses, labor unions and advocacy groups kicked off its push Thursday to get the Legislature to approve an infusion of money to improve Minnesota roads and transit, likely through a gas tax increase.

Members of the coalition, Move MN, argued that the state’s transportation system isn’t keeping up with economic growth. The Legislature last raised Minnesota’s gas tax in 2008 and coalition members said it no longer raises enough money to keep up with growth — particularly as federal funding sources dry up.

The coalition will test whether political will exists for another increase. Democratic Gov. Mark Dayton, who has advocated greater state investment in transportation, nonetheless has said he expects election-year pressures to make transportation tax hikes a tough sell.

Last year, the state Senate approved a 5-cent gas tax increase and a half-cent sales tax hike in the seven-county Twin Cities metro area that together would have raised about $1 billion over four years for transportation upgrades. But it never came to a vote in the House. Rep. Frank Hornstein, the Minneapolis Democrat who chairs the House Transportation Finance Committee, said he expected a similar package would be considered again this year.

“Clearly there’s a lot of support for this, but there are some members that are concerned as well,” Hornstein said.

Last year, the Democratic-controlled Legislature approved both upper-income tax hikes and a range of sales tax increases on business, which could make many lawmakers reluctant to increase even more taxes this year.

Minnesota’s current gas tax is 46.5 cents per gallon.

Rep. Mike Beard, of Shakopee, is a leading Republican on transportation issues and said he didn’t expect any support among his GOP colleagues in the Legislature for increases in the gas tax, motor vehicle registration fees or other traditional sources of transportation revenue.

Members of the Move MN coalition, which number some 130 groups statewide, said they hope to convince lawmakers that the need is dire.

“We have fallen so far behind in our transportation needs, and we need to have funding sources that are sustainable,” said Margaret Donahoe, executive director of the Minnesota Transportation Alliance. She cited recent studies showing that more than half the state’s roads and bridges are in mediocre to poor condition, and that only 10 percent of workers in the Twin Cities have convenient access to transit.

But notably absent from the Move MN coalition is the Minnesota Chamber of Commerce, which was a prime political force behind the last gas tax increase in 2008, when the Legislature overrode then-Gov. Tim Pawlenty’s veto of the nickel-a-gallon hike. Bentley Graves, the chamber’s transportation policy analyst, said its member businesses aren’t ready for another increase.

“A lot of businesses are still grappling with the tax increases they saw last year,” Graves said. “What we’re looking for is a focus on stretching the dollars currently being invested, and using them as wisely as possible.”