A Metro rail extension from southern Houston to Missouri City is gaining momentum, fueled by rare near-unanimous support from local, state and federal officials who represent the area.

The hope is one day whisking commuters from Fort Bend County into the Texas Medical Center and other nearby job hotspots. As the rail project picks up speed, a few officials, however, worry the transit agency might get ahead of itself to the detriment of other possible bus and rail improvements as money and resources perhaps shift to the rail line.

"I don't know that I see it as being the next project," said Metro board member Lisa Castaneda, who urged officials to slow down on some aspects of studying the rail link and soliciting possibilities for private investment in it.

The issue touched off a sometimes-contentious exchange last week between Metropolitan Transit Authority board members, though most were supportive of moving forward with some of the rail plan. Still, even those eager to advance the rail project stress Metro has not made any final decisions and still has no sure way to pay for it despite vocal support from U.S. Reps. Al Green, D-Houston, and John Culberson, R-Houston.

"Metro needs to accelerate their work on the 90A rail and make it their top priority when and if they have the funding to build it," said Culberson, who also has sometimes been a strong opponent of particular rail expansion.

That bipartisan support, buoyed by a chorus of local officials, gives Metro a rare opportunity to muster political clout for the line, though light rail always will be a contentious discussion in the Houston area, as differences arise over what should be the next high-priority project. In July, Metro approved restarting discussions with the Federal Transit Administration about the 90A rail line. Federal approval is critical, as money from Washington is a huge part of affording any light rail project. Two of the three light rail projects Metro has opened since 2013 each received $450 million in federal dollars, which covered more than half the total cost.

The line, as initially devised and conceptually approved by voters in 2003, would run from the Fannin South light rail station where the Red Line terminates to Missouri City. When officials suspended development of the project in 2012 as Metro focused on getting other rail lines built, the line was expected to cost $400 million to construct. Missouri City, though not Fort Bend County, is a member of Metro and has clamored for a rail link for years. The line likely would follow U.S. 90A, along existing rail corridors for about 9 miles, and offer an alternative to driving for some commuters, possibly as far away as Sugar Land.

"Given the importance of the 90A project and the completion of other Metro projects, I think it is logical and reasonable that Metro is now accelerating the pace to realize this voter-approved and highly beneficial project," Green said. "The 90A rail project will serve as an emergency evacuation route. It will connect thousands of residents in large residential communities, such as Missouri City and Stafford to downtown Houston and the Texas Medical Center and create thousands of jobs."

Putting on the brakes

At a Metro committee meeting earlier this month, board members had what one called a "spirited" discussion about potential private investment in local commuter rail projects. The discussion was prompted by a request for information prepared by Metro staff, which could be circulated to gauge interest in development deals.

Metro board Chairwoman Carrin Patman said while agency staff members were authorized to release the request without board approval, she sought their input before sending it out. The action, however, was delayed when board members, primarily Castaneda, chafed at moving ahead.

While not opposed to the rail line - as it requires much more study - Castaneda balked at some of the eagerness other board members showed to press ahead and seek proposals from private developers interested in joining with Metro for a Missouri City rail line.

"I am not optimistic we are going to get back a product that doesn't require a lot of commitment from Metro," Castaneda said.

Patman countered during the discussion that transit officials won't know their options unless they explore them, especially when local elected leaders are eager to press ahead. Mayors, including those outside the Metro service area such as Stafford Mayor Leonard Scarcella, have offered full-throated support for the line for more than a decade.

"The lost capital of not doing something … is going to send I believe the wrong signal, and I believe a very costly one," Patman said.

Green, who has committed to use his position in Congress to muster support and potentially federal money for the line, said "it is my hope that the real prospects for this continue to move forward judiciously as well as expeditiously."

The agency exhausted all of the referendum money extending the Red Line and building the Green Line along Harrisburg and Purple Line along Scott. Along with 90A, voters also approved plans for what's referred to as the University Line - though that rail project has languished as criticism to its route on Richmond was strengthened by Culberson's stiff opposition.

With Metro unable to borrow more money without voter approval and expecting sales tax revenue to stagnate, officials are considering a variety of other options for the 90A rail line, including the possibility of a public-private partnership.

Looking to Denver

Much of the recent Metro committee discussion focused on a Denver transit project - the first completed public-private partnership involving a transit project in the nation - that used $450 million in private investment to build 40 miles of light rail at a cost of $2.2 billion. The investors in Denver then operate the rail line, repaid via annual payments by the local transit agency, as well as have an opportunity to develop properties along the route.

Though a possibility, Metro board members said private investment comes with risks of its own.

"Any (public-private partnership) model is going to involve this agency making yearly payments to pay off the debt and making yearly payments to operate it," Metro board member Christof Spieler said.

Though that might make sense and has obvious advantages - such as building the line sooner - Spieler said "one of those advantages is not a money tree."

Metro also faces many more investment needs beyond commuter rail, including new buses and adding park-and-ride locations. Spieler said a 90A commuter rail line would be an entirely new cost, unlike the recent rail lines that allowed Metro to shift money used to operate buses along those streets now served by rail.

Excitement for the rail line to Missouri City outpacing reality is something Metro must consider, board member Cindy Siegel said.

"This board has been taking steps and giving the signal to elected officials," she said, citing the revived interest earlier this year in 90A. "If that's not it... I think we need to quit giving the signal."