As the clock ticks toward May 31, when highway and transit authorizations are set to expire, congressional lawmakers are working on potential successor bills but so far haven't found the revenue needed to fund that new legislation.

The key House player, Transportation and Infrastructure Committee Chairman Bill Shuster (R-Pa.). held a three-hour hearing on Feb. 11 whose sole witness was Transportation Secretary Anthony Foxx.

Most of the panel's 59 members were there and each got about five minutes to quiz Foxx about an array of issues, some dealing with the coming major highway-transit bill and others focused on issues particular to lawmakers' respective districts—to no one's surprise.

Foxx outlined the Obama administration's six-year, $478-billion proposal, unveiled on Feb. 2, and its partial "pay-for," a one-time 14% tax on U.S. companies' overseas income. He urged lawmakers to aim for a substantial amount of funding. "We've got to go big," Foxx said.

After the hearing, Shuster and Foxx took a few minutes to speak with reporters before they began a Twitter session answering transportation questions.

Shuster gave a status report on the legislation. "We're drafting right now," he said. "But the driving force behind [the bill]  is going to be the funding. We don't want another two-year bill. We want a five, six-year bill. As the Secretary pointed out today, that's what the administration wants."

Shuster said he's waiting for the tax-writing committees, House Ways and Means and Senate Finance, to develop a revenue plan. "We're talking to them on a daily basis, trying to help them figure out where to go for funding."

He said he felt if would be "counterproductive" for his committee to unveil a measure dealing with all of transportation bill's policy provisions and other non-revenue items.

Instead, Shuster said, "We ought to wait 'til we get the funding and then let's craft a bill that we [will] know what the time frame is....That makes more sense for me."

Time is running short. Foxx told the committee that if no new bill in place by the May deadline, sometime around June U.S. DOT will start notifying state transportation agencies that it will have to begin husbanding its cash, by sending out reimbursements less often than now.

DOT sent out such a noticelast July when the Highway Trust Fund's highway account faced the prospect of tumbling into a deficit. Congress rescued the fund by passing a 10-month, $10.8-billion "patch."

That situation may be repeated unless Congress acts again.

Already, Foxx observed, some states are pulling back on their 2015 highway contracting. He told  reporters, "If we go over the cliff in May, we will have to start going through the process of cash-management procedures and so forth—just like we did last year."

After the hearing, Shuster gave public-transit advocates encouraging news. At least a couple of other committee members raised the question of continuing to fund transit out of the Highway Trust Fund, which is largely supported by motorists' gasoline and diesel taxes.

But Shuster seemed disinclined to decouple transit from the trust fund. He cited "the lessons of history," and recalled, "We tried to pull [transit] out before we did [2012's] MAP-21, "and we had a revolt on our hands."

Shuster added, "The logic behind [trust-fund transit funding] makes sense to me, that if you take people off the roadways and put them on buses and transit systems, you make more room on the roadways. Ronald Reagan cut that deal back in  the '80s....It's very difficult to back that out."

Asked whether he could get a bill done by May, Shuster said, "That's our goal." "Our eye's on the prize...getting something done by the end of May—and we're going to stay focused there until we realize we may not be able to do it. And right now, we're focused."