With only 18 days until highway and transit authorizations run out, and no Senate-House deal in sight on a longer-term transportation measure, key negotiators from each chamber are firing some verbal volleys at each other.

Senate Environment and Public Works Committee Chairman Barbara Boxer (D-Calif.) appeared at a June 13 "get the bill done" rally near the base of Capitol Hill, along with seven other Senate Democrats and representatives of transportation and construction industry groups.

House and Senate conferees, and their staffs, have been meeting and communicating since May 8 to work out differences between a $109-billion, two-year highway-transit bill that the Senate passed in March and a three-month extension (with some controversial non-transportation provisions) that the House cleared in April. The critical date is June 30, when a stopgap authorization lapses.

With five concrete mixers and a tractor-flatbed trailer rig parked on the street behind her, Boxer told the gathered supporters and reporters, "There is only one group standing in the way of the bill....That group of people that's standing in the way of jobs and business—those are the House Republicans. That's the facts. And that's the truth."

Sen. Charles Schumer (D-N.Y.) said not all Republicans are blocking the legislation. But then he ratcheted up the rhetoric, pointing to "a hundred [House Republicans]—militants, radicals, extremists—who actually believe the federal government should not be involved in highway building."

After the rally ended and the construction vehicles had rumbled away, House Transportation and Infrastructure Committee Chairman John Mica (R-Fla.) responded.

Mica said in a press release that he's "hopeful" a deal can be struck with the Senate, but added, "I am disappointed in the fact that Senate negotiators have yet to move on key House reform proposals"—an apparent reference to proposals to consolidate highway and transit program categories and to speed the project approval process.

He also said, "In addition, the Senate appears unwilling to compromise at all on the Keystone XL pipeline." The House bill included language aimed at gettng quick U.S. approval for the proposed oil pipeline, which would run from Alberta to the Gulf coast.

The House is on a break this week, but Mica said he would "confer" with the rest of his House negotiating team on June 14 to discuss the status of the transportation talks with them.

Boxer did say that he two sides "have been negotiating in good faith, exchanging proposals." She added, "We are passing back and forth big chunks of the bill and we are making progress in terms of our negotiation." 

House Speaker John Boehner (R-Ohio) had said last week that if there isn't an agreement on a longer term bill by June 30, he foresaw "a six-month extension [that would] move this thing out of the political realm that it appears to be in...."

But 17 transportation and construction industry groups sent a letter to Boxer and the other 46 transportation bill conferees on June 13, urging them to agree on a long-term bill by June 30.

They said: "A six-month extension is not the way to go. This approach could further exacerbate the Highway Trust Fund's financial crisis and cause states to cut back on transportation investments during what should be the peak construction season."

Boxer said that an extension that doesn't include an infusion of additional money "bankrupts" the trust fund by early 2013. "The fund [would be]  gone," she said, "Over, out, done."

The rhetoric may be a tactic by each side to nudge the other towards an agreement. Or it could just make them more entrenched. Meanwhile, June 30 is drawing nearer.