AUGUSTA, Maine — A Democratic senator from Lewiston wants the Legislature’s investigative arm to look into the Maine Turnpike Authority’s pending proposal to raise tolls on the 109-mile Maine Turnpike, saying the toll hikes would disproportionately fall on the backs of residents of the Lewiston-Auburn area and western Maine.

Sen. Margaret Craven on Friday will request that the Legislature’s Office of Program Evaluation and Accountability, or OPEGA, probe the authority’s proposal for toll hikes designed to raise an additional $26 million in revenue annually.

“I’m hoping that they will look at the disparity and look at the burden it places on people going to work or shopping from this region,” said Craven, a member of the Legislature’s Government Oversight Committee. “Is that fair?”

She also wants the independent examination to look into why the toll hike needs to take place this year. The Maine Turnpike Authority board could vote as soon as July 19 on a toll hike, and the authority is proposing that the changes take effect Nov. 1.

“To me, I don’t see the urgency,” Craven said. “If there was a plan [for paying off the bonds], that should be followed.”

The request for an investigation into the turnpike toll hikes is the latest in a series of complaints from residents of the Lewiston-Auburn area, who say the toll hike proposal favored by turnpike authority staff disproportionately affects their region. One Lewiston legislator, Democratic Rep. Michael Carey, is collecting signatures in an effort to stop the toll hike and have any toll hike considered by the Legislature.

“Whether we’re going north or south, we’re paying constantly,” Craven said. “It costs me $7 round trip to go to Portland.”

The current proposal would hike tolls by $1 at the toll plaza in York, 75 cents at tolls in New Gloucester and West Gardiner, and 50 cents at tolls in Wells and Gray. The proposal also would raise the per-mile rate for users of the E-ZPass toll transponder to 8 cents from the current 6.7-cent rate.

Peter Mills, executive director of the turnpike authority, has suggested to drivers concerned about inequitable tolling at certain turnpike exits that they purchase E-ZPass transponders and pay a per-mile rate for using the highway.

Mills says the Maine Turnpike Authority needs to generate $26 million annually in additional revenue to fund $113 million in bridge repairs on northern sections of the 109-mile highway over the next five years, pay for $82 million in paving and other road improvements, and pay off debt from a highway widening project completed in 2004.

Revenue growth for the turnpike has largely leveled off, he says, and the turnpike needs to take in a certain amount of revenue in order to comply with the terms of its debt and avoid a default. The turnpike authority takes in about $103 million annually from tolls and another $3 million each year from operating its service plazas.

If Craven’s request for an OPEGA investigation into the toll increases is approved, it would be the second OPEGA investigation into the Maine Turnpike Authority in recent years. An examination by the agency in 2010 turned up more than $200,000 in authority spending that could not be accounted for. That finding ultimately led to a theft conviction and prison sentence for the authority’s then-executive director, Paul Violette.