After plunging into the deep freeze last year, the World Trade Organization's "Doha round" of talks seems to have perked up after a flurry of high-level contacts in recent weeks.

But as WTO director-general Pascal Lamy underlined on a visit to Washington this week, which was dominated by meetings with members of Congress, time is of the essence and there is "no plan B" should Doha fail.

WTO members face an uphill battle to conclude a deal before June 30, when US President George W. Bush's "Trade Promotion Authority" (TPA) to speed such pacts through Congress expires.

Speaking after talks Wednesday with US Trade Representative Susan Schwab, Lamy said the Doha round was "nearing crunch time" on the pivotal issues of agricultural trade and industrial market access.

"We need Congress to be aware that activity, motion, determination, progress in a renewal of Trade Promotion Authority is important for the momentum in the negotiations," he said.

The WTO chief said it was up to the big developing countries to play a breakthrough role along with the two most powerful players in the process, the United States and European Union.

Only through concessions from the likes of India and Brazil can the US Congress even entertain the idea of renewing TPA. "It's much easier to do that with something on the table than in a sort of vacuum," he said.

This month in New Delhi, Schwab and trade chiefs from the EU, India, Brazil, Australia and Japan said they believed that through harder work, "we can reach convergence and thus contribute to concluding the round by the end of 2007."

The Doha round, launched in 2001 in the Qatari capital, has repeatedly missed deadlines as wealthy and developing nations have struggled to strike a deal on opening up trade in agricultural, industrial goods and services.

The meeting in the Indian capital marked the first time the leading trade powers had assembled for talks since the Doha discussions collapsed last July.

Even if a quick breakthrough can be achieved, and that remains an open question, the TPA issue is a major complicating factor.

The Democratic-led Congress shows little appetite for handing Bush a new fast-track authority, and thus from June is likely to regain the power to take apart any trade deal line by line.

And as noted recently by Max Baucus, the Democratic chairman of the Senate's powerful finance committee, there is still less incentive to renew TPA without the impetus of a Doha deal on the horizon.

"Obviously the content of the outcome is more important than a specific deadline and I suspect Pascal heard that from the (Capitol) Hill," Schwab said.

"Let's step up the pace to see if we can get this done and shoot for the end of the year, give or take," she added.

The "G4" group of leading WTO actors -- the EU, United States, Brazil and India -- plan a series of ministerial meetings over the next two months, starting in Paris in mid-May.