At their final meeting Friday, leaders of a three-county citizen advisory panel tried to step back from sensitive particulars about when to build new rail transit service across the Triangle -- and how to pay for it.

Members of the Special Transit Advisory Commission voted with a unanimous show of hands to call for a new half-cent sales tax as the main local funding source for bus and rail projects over the next three decades. They rebuffed a call by their co-chairman, George Cianciolo of Chapel Hill, to avoid the touchy specifics of how local politicians should address the need for transit money.

The 29 civic and business leaders have been meeting since May to rethink long-term bus and rail transit priorities for Wake, Durham and Orange counties. City and county elected officials hope to receive their recommendations later this month.

At their 15th and final meeting Friday in Research Triangle Park, several members said their report should not shy away from tough political issues.

"One of the reasons we were established was to do some thinking," said Cal Horton, Chapel Hill's former town manager. "Another reason was to take some of the heat off the governing bodies. Well, let's take some heat."

Some county officials and legislators have said that a sales tax increase would be regressive, unfairly burdening the poor.

But commission members said poor residents stand to benefit most from a key part of the plan -- the quick purchase of 120 new buses to boost regional and local bus service.

"The sales tax isn't as regressive as our current transportation system -- where, if you don't have a car, you can't get to work," said Mike Shiflett, a Durham neighborhood leader.

Commission members said elected officials should not block a sales tax referendum.

"We should tell them, 'We want you to put this on the ballot, to give the people in our community the right to decide,' " said Tom Bradshaw, a former Raleigh mayor and former state transportation secretary.

The advisory group raised eyebrows when it tentatively agreed Feb. 4 to an ambitious plan for new bus service; bus or trolley "circulators" in downtown areas and in RTP, with a link to the airport; and a $2 billion investment in 56 miles of rail transit lines that would be built by 2020.

Some Raleigh business leaders complained privately that the plan was too big and too costly to win voter support. This week, the panel's four leaders circulated a draft rail plan, endorsed by the president of the Greater Raleigh Chamber of Commerce, that would postpone an 8.5-mile link from RTP to northwest Cary until after 2020.

"Let's face it, the year 2020 was not a realistic year," Co-chairman Bill Cavanaugh of Raleigh told commission members Friday. "And the real cost was substantially more than $2 billion. You need to forget about 2020, and let's talk about sequencing and prioritization -- because that's the next step."

The Cary-RTP train link "will come, but it's probably going to come later down the road," Cavanaugh, retired CEO of Progress Energy, told the group.

As Friday's six-hour meeting ended, it was not clear what the final report would say about key details, including the sales tax and the Cary-RTP link. Cavanaugh would not say whether he would campaign for a sales tax increase.

Smedes York of Raleigh, one of the advisory group's leaders, said the entire 56-mile rail system was still in the plan to be built by 2035, but he wasn't sure which part should come first or last.

Cavanaugh suggested the final report would refrain from conclusions about which rail links to build first, or whether the trains would start running by 2020.

Cavanaugh said more study is needed.

"We're going to start aggressively studying the rail corridors," he said in his closing remarks. "Sequence them as, if it turns out that if one's ready to go, it will be the first one up."