US President Barack Obama says he'll ask Congress for $US300 billion ($A335.59 billion) to update ageing roads and railways, arguing that the taxpayer investment will pay dividends by attracting businesses and helping put people to work.
Funding for surface transportation programs expires later this year, and the White House says 700,000 jobs could be at risk unless Congress renews them.
"At a time when companies are saying they intend to hire more people this year, we need to make that decision easier for them," Obama said, by rebuilding ageing transportation systems, power grids, communications networks and other projects that ease commerce.
"The bottom line is there's work to be done, workers ready to do it," he said, adding that one of Congress' major responsibilities is to help states and cities pay for such projects.
Transportation Secretary Anthony Foxx warned on Wednesday of a "transportation cliff" coming in August or September when the Highway Trust Fund, which finances federal highway and transit projects, is forecast to go broke.
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The trust fund will need an influx of $100 billion over the next six years just to maintain transportation spending levels. But Obama and Congress have been unwilling to raise federal gasoline and diesel fuel taxes that have been the main source of federal transportation funding for decades.
AAA, the automobile association, on Wednesday criticised Washington's refusal to increase fuel taxes to pay for projects.
In the budget he sends Congress next week, Obama will propose that half of the $302 billion he's seeking come from an overhaul of the corporate tax system.
