[Senator Lee Constantine, center, answers questions from the Capitol press on the Sunrail debate. Scott Keeler, Times]

Backers of the $1.2-billion purchase of CSX rail track in Central Florida for a commuter rail project suffered a major defeat Thursday in the Senate. By a 23-17 vote, senators refused to allow a late-filed amendment to be taken up that was crafted to win over crucial votes of South Florida Democrats -- by providing a new rental car tax for Tri-Rail in that region. Twelve of those no votes were Republicans, an ominous sign indeed for a project being pushed by Gov. Charlie Crist and much of the Central Florida business community.

"It doesn't look good," said former House Speaker John Thrasher, a member of the army of lobbyists pushing the project known as Sunrail. "I'd say it's on life support at best."

 It was the last bill the Senate took up Thursday. A final vote was not taken, but it looks as though Sunrail's leading opponent, Sen. Paula Dockery (right), R-Lakeland, is in a commanding position.

During discussion of the project itself, one Republican after another asked tough questions of the project's champion, Sen. Lee Constantine, R-Altamonte Springs. Leading the charge in opposition were Sens. Mike Bennett, Charlie Dean, Jim King< Evelyn Lynn and Ronda Storms -- all Republicans. They questioned the cost, levels of expected ridership, and the state's legal liability if a CSX train struck a busload of school children in the rail corridor.

"I like the idea of light rail," Bennett said. "I just don't like bad business deals for the state of Florida. I think we should renegotiate something we are overpaying for."

Constantine eventually withdrew his own amendment that would have called for a 2010 referendum on the rental car surcharge, but allow a county commission to re-impose the rental car tax even if the voters had rejected it. "Do I have a chance? You always have a chance. Is it good? No," Constantine said.