With Congress riven by partisan politics and facing a truncated election-year schedule, the chances are slim that it will pass a long-awaited bill to fund the nation’s highways, mass transit and ports, U.S. Transportation Secretary Ray LaHood said Wednesday.

LaHood’s gloomy forecast came two days before House Republicans are expected to begin circulating their five-year transportation blueprint, a $260 billion bill that may be introduced as early as next week.

In spanning five years, the House proposal already is at odds with a two-year Senate plan that cleared a committee last year. It will include far-reaching reforms to the federal transportation bureaucracy while transferring significant authority over spending decisions to the states.

“I believe we’ll probably have to wait until next year to get to a surface transportation bill because of the huge differences,” LaHood told a conference of transportation experts meeting in Washington. “Given the politics, the number of days that remain, the differences between what the Senate and the House are looking at, I think it’s very unlikely that we’ll have a surface transportation bill during this year.”

The certainty of long-term funding is considered essential by federal and state planners charged with launching long-term projects. Yet Congress has proved itself incapable of agreeing on the critical surface transportation funding bill. The last long-term bill expired almost three years ago and transportation planners have been hamstrung by eight short-extensions.

Though transportation is eclipsed in the budget debate by the deficit, defense spending and entitlement programs, alarms have been raised for more than a decade about the impact that a deteriorating transportation infrastructure will have on the nation’s long-term economic health.

The American Society of Civil Engineers has estimated that an investment of $1.7 trillion is needed between now and 2020 to rebuild roads, bridges, water lines, sewage systems and dams that are reaching the end of their planned life cycles. The Urban Institute puts the price tag at $2 trillion.

A 2010 report by 80 experts led by former transportation secretaries Norman Y. Mineta and Samuel K. Skinner called for an annual investment of $262 billion.

Even when Democrats had command of the House and Senate, they weren’t able to produce a long-term surface transportation bill because revenue from the federal gas tax no longer provides the robust funding levels that were used to launch the interstate highway system 60 years ago.

LaHood sat on a panel at the Transportation Research Board’s annual meeting Wednesday with five former transportation secretaries, and none of them provided a ready solution for revitalizing the Highway Trust Fund, which is supported by the federal gasoline tax of 18.4 cents per gallon.

“The Department of Transportation has become a bank, managing trust funds,” said Andrew H. Card Jr., who served as transportation secretary during the administration of George H.W. Bush. “And many of those trust fund balances aren’t large enough to meet the expectations of the owners of the trust.”

The owners of the trust, U.S. taxpayers, have to realize they can’t have everything they want, he said.

“We have not had the courage to really argue about what the basic needs of transportation are,” Card said. “This is the competitive needs of the nation, not the need for an off-ramp to a supermarket.”

Alan Boyd, who led the formation of the Transportation Department during Lyndon B. Johnson’s administration, put it more bluntly.

“So many of my fellow Americans want to have good roads, good bridges, but they don’t want to pay for them,” Boyd said. “They want somebody else to pay for them. No new taxes.”

President Obama raised the infrastructure issue in his State of the Union address on Tuesday, disappointing some transportation experts who had hoped for something more specific than the suggestion that money saved by winding down wars could be spent on infrastructure.

“So much of America needs to be rebuilt,” the president said. “We’ve got crumbling roads and bridges. There’s never been a better time to build, especially since the construction industry was one of the hardest-hit when the housing bubble burst.”