WASHINGTON - Moments before Minnesota Democrat Jim Oberstar planned to roll out his $450 billion transportation makeover last month, he was called to an adjoining room in the Rayburn House Office Building. There, he was confronted by Transportation Secretary Ray LaHood, who told him that the Obama administration wanted him to hold off on his bill for 18 months.

Floored by the news, Oberstar pressed forward with the legislation anyway -- setting him on a collision course with the White House over his plan to transform the nation's transportation policies in the next six years by improving infrastructure and speeding up investments in trains and mass transit.

Though it appears to be an uphill climb in the Senate, where some key Democrats have acquiesced to the president, Oberstar has become increasingly critical of the White House. He continued the drumbeat Thursday. "We don't need an 18-month learning curve," he told members of the House Transportation Committee, which he chairs.

He also made clear his intention to pass the bill in the House with support from Republicans, some of whom have expressed sympathy for his predicament. "I've never seen a chairman undermined by an administration in the 30 years I've been around this place like they hosed our chairman," said Rep. John Mica of Florida, the ranking Republican on the committee.

At stake are billions of dollars in projects throughout the country, including funding for the Central Corridor light-rail line in the Twin Cities and the extension of the Minneapolis-based Northstar commuter rail line from Big Lake to St. Cloud.

Though the Obama administration has aligned itself with much of what Oberstar wants to do, there is no consensus in Congress on how to pay for the massive transportation improvements he envisions.

The most obvious revenue source -- the federal gas tax, 18.4 cents per gallon -- hasn't been raised in nearly two decades, and the administration is reluctant to propose an increase in the midst of a recession.

Sen. Barbara Boxer, D-Calif, who heads the Senate committee that deals with public works, moved this week to approve the 18-month delay, arguing that it would be difficult to increase the gas tax in the near term even with the support of labor groups and the U.S. Chamber of Commerce, which has called on Congress to pass Oberstar's bill.

State officials say the highway bill could serve as a permanent stimulus to supplement the $787 billion package Congress approved this year to create jobs and lift the nation out of recession. "Our concern is whether the funding for projects continues the momentum of the stimulus," said Serge Phillips, federal relations manager for the Minnesota Department of Transportation.

Among the revenue options being floated in Washington are new taxes on imported oil and on speculators who trade in oil futures. But given the current climate in Congress, where lawmakers are scrambling for revenue sources to pay for health care reform and new curbs on carbon dioxide emissions, the Obama administration remains cool to any quick action on the highway bill.

Roy Kienitz, undersecretary for policy in the Transportation Department, told Oberstar's committee on Thursday that there is "widespread agreement" about reinvesting in the nation's aging transportation infrastructure. But, he added, "We cannot achieve our goals" with the kind of bill Congress would be likely to pass this year.

Under the White House proposal, current funding levels, which are due to expire Sept. 30, would be extended until March 2011. That's a delay, Oberstar said, that a traffic-choked nation can ill afford.

Kevin Diaz • 202-408-2753