DENVER -- Metro area mayors agreed Wednesday to recommend to the Regional Transportation District Board to add another four-tenths of a percent sales tax to bridge the $2.2 billion funding gap for the FasTracks project.

RTD now has to go to the voters, who will decide this November whether or not to approve the tax. The 0.4 percent sales tax would equal 4 cents for every $10 a consumer spends.

At the general meeting of the Metro Mayors Caucus Wednesday, the 38 metro area mayors said the tax is needed in order to complete the FastTracks project by the original date of 2017. Cost estimates of the project have increased and sales revenue is down, creating the $2.2 billion hole.

FasTracks would expand light rail throughout Denver to the metro area cities of Aurora, Lakewood, Golden, Arvada, Wheatridge, Bow Mar, Westminster, Superior, Broomfield, Boulder, Longmont, Thornton, Northglenn, Highlands Ranch, and Littleton.

Without the money, the mayors said the project would have to be scaled back, and certain cities would have to wait or lose parts of the light rail lines.

Taxpayers are currently paying four-tenths of a percent for FasTracks, having approved of the original tax in 2004. So if the new tax is approved, 8 cents of every $10 a person spends in the metro area would pay for FasTracks.

Mayors said there is also a gap to fund operational and maintenance expenses once the project is complete. So besides making up for the budget shortfall for the original project, the new tax money would also go to operational gaps.

The mayors struggled with the tax amount wondering if another 4-tenths-of-a cent would be enough to fund the project because they did not want to go through the process of asking for another tax hike, but they did want it approved by voters.

Another key issue the mayors were concerned about is when the tax would sunset. The current tax ends when the bonds for construction of all of the projects are paid but some portion of the tax will be retained in perpetuity to fund the operations and maintenance of the light rail system.

The mayors' recommendation will be presented to the RTD board at their next regular meeting on March 31. If the board approves of the recommendation, which is expected, the board will come up with the ballot language and present the issue to the voters.

RTD says they expect a tough fight to get the voters to approve of a new tax in such a down economy.

In January, RTD commissioned a poll of 700 likely voters and found 64 percent either strongly or somewhat support a tax increase and 35 percent were strongly or somewhat opposed to an increase.

The mayors' caucus agreed that asking voters now is better than waiting for 2010 when the economy is expected to be in better shape.