LAFAYETTE — The Lafayette City-Parish Council would give up some of its power in deciding where federal transportation dollars are spent under a proposal unveiled Tuesday.

At issue is the possible restructuring of the Metropolitan Planning Organization, a federally mandated group that decides how to spend federal transportation dollars passed down to local government.

The MPO is supposed to represent a regional metropolitan area that is tied together by population densities and commuter patterns, and that metropolitan area has expanded into all the surrounding parishes under a federal re-evaluation that followed the 2010 census.

The nine-member Lafayette City-Parish Council has served as the MPO since the 1990s, but the proposal unveiled Tuesday would double membership in the group to 18, bringing in representatives from surrounding cities and parishes surrounding Lafayette.

The new MPO group would have the final say on how to spend the roughly $10 million annually in federal dollars available for transportation and transit projects in the metropolitan area, Lafayette City-Parish Planning Manager Mike Hollier said.

He characterized the change as the council “relinquishing its authority” to a reconstituted MPO group that would decide who gets money and for what projects.

Councilman Jay Castille said Lafayette Parish would still have 10 of the 18 votes in the proposed group — the nine members of the City-Parish Council and a representative of the city-parish president.

“We are still a majority,” Castille said.

Still uncertain is how the proposal will be received by other cities and parishes, which in return for representation on the MPO would be asked to help pay staffing and facilities expenses related the transportation planning for the region.

Hollier said the incentive for helping cover those expenses is that the other cities and parishes would be given a voice in how the federal transportation fund are spent.

“If they are not a member ... the odds are strongly against them getting any funds,” Hollier said.

Hollier said he plans to begin presenting the proposal to officials in surrounding parishes.

If everyone can agree on the details, the new MPO group could be in place by the end of the year, he said.

Representation on the MPO became an issue in 2009 when the Lafayette area received about $8.3 million in one-time federal stimulus money for road projects.

Some leaders from surrounding parishes questioned why the Lafayette City-Parish Council should have had sole authority in deciding where the money went when the federal dollars were supposed to be for the entire metropolitan area, which included areas outside of Lafayette Parish.