The majority of Charleston-area residents want Interstate 526 extended, local elected officials said Friday, and they have banded together to send that message to the state Department of Transportation.

A panel of high-powered leaders gathered for a news conference to make presentations on why they thought the extension of the Mark Clark Expressway across Johns and James islands was important.

Their reasons included relieving severe traffic congestion in the growing region, improving hurricane-evacuation routes and linking together local communities.

In order to complete the project, they said, they must demonstrate to the DOT that it has widespread community support and that money was available to pay for it. And they think they can do both of those things.

They also said they think a vocal minority of opponents were holding up the project, making it appear that most residents were against it when most actually support it.

Charleston County Council Chairman Teddie Pryor and Vice Chairman Elliott Summey; Charleston City Councilman Bill Moody; state Reps. Bobby Harrell and Leon Stavrinakis; and Mayors Joe Riley of Charleston, Keith Summey of North Charleston and Billy Swails of Mount Pleasant participated in the event.

“I-526 is incredibly important to the Lowcountry,” House Speaker Harrell said. “If we don’t finish it, 20 or 30 years from now, our children and grandchildren are going to say, ‘What is wrong with you?’?”

Jake Libaire, a project manager for the Coastal Conservation League, which is opposed to extending I-526, said the news conference was “more a PR event.” No new information was presented, he said.

His group, along with others, such as Nix 526, continue to think other local road projects are more important to the area than I-526, and that it is an unwise way to spend more than $500 million the work would cost.

County Council in January voted to give up control of the long-stalled project. Members voted 7-2 in favor of turning it over to the DOT, hoping that would free the county from having to pay back $11.6 million already spent on the project. The DOT has not yet agreed to take control of the work.

Harrell, Stavrinakis and Riley said that DOT representatives have told them that in order to take it on, local leaders need to demonstrate widespread local support for the project, and that there is money available to pay for it.

All the leaders at the news conference said the majority of their constituents have told them they support the project. And voters approved the road in a referendum, they said.

On the financial side, $420 million is available for the project, while the current estimate to complete it is $556 million.

The Berkeley-Charleston-Dorchester Council of Governments’ transportation committee, of which Elliott Summey is chairman, last month updated the project’s cost estimate. At the time, Summey said a current cost estimate was required for the DOT to take on the project.

On Friday he said that when the 44-member group updated the estimate, it effectively removed any risk that the DOT would have to cover a shortfall.

The Council of Governments’ group receives between $6 million and $10 million in federal money for transportation projects each year, Summey said.

And that money could be used for projects on the group’s long-range priority list. The I-526 extension is on the list, he said.

But, he added, he and other leaders think the $556 million estimate is high.

Summey thinks the project could be modified and completed for about $420 million, the money on hand for the project.

DOT spokesman Peter Poore said the department is continuing its discussions with the State Infrastructure Bank about taking on the project.

He said he could not provide more information on when a final decision on whether to take on the project would be made.

Reach Diane Knich at 937-5491 or on Twitter @dianeknich.