Faced with an uncertain flow of federal highway funding, Florida transportation officials are working to identify road construction projects which can be frozen or scrapped if the need arises.

The extraordinary preparations follow the failure of Congress to fully renew the nation's Highway Trust Fund before lawmakers left Washington for their summer recess.

The fund supplies a quarter of Florida's transportation funding needs, amounting to $2.4 billion this year alone.

Though the state has a reserve that can maintain current spending on road projects for three to six months, officials want to have a plan in place should a full renewal of the Highway Trust Fund not come to fruition by the end of the year.

"There potentially could be a six-month window where we would need to take a look at whether or not we would need to slow down some projects," said Matt Ubben, president of the group Floridians for Better Transportation, pointing to the I-4 Ultimate makeover in Central Florida and widening of I-75 and I-275 in the Tampa Bay area as road project behemoths that could be affected.

The congressional intransigence is primarily the result of Republican opposition to raising taxes in order to ensure the solvency of the Highway Trust Fund. Members of both parties are loath to increase the federal gas tax, which is the traditional source of the fund's revenue.

Democrats, however, have called for raising money through closing offshore tax loopholes.

"The American people are tired of this Republican Kabuki dance," U.S. Sen. Bill Nelson (D-Florida) said at a July press conference aimed at convincing the Senate's majority Republicans to support legislation to close the loopholes. "We are here to say that it's time to stop this nonsense, and let's just get the roads repaired and built."