Lockheed Martin Corp. appears to have won a fierce and protracted competition to build a fleet of 48 fighter jets for the Polish air force, a $3.5 billion affirmation of the military and political firepower still wielded by one of the company's oldest and most lucrative products - the F-16 Fighting Falcon.

A formal announcement from Warsaw is not expected until today, and Lockheed Martin officials said they have received no word from the Polish government. But the chief executive of Dassault Aviation SA, another contender, said on French radio yesterday that Lockheed Martin has been selected.

If it is declared the winner at a noon announcement today in Warsaw, Lockheed Martin's 27-year-old F-16 will have beaten out two of Europe's modern and sophisticated fighters: the French Mirage and the Swedish Gripen.

Also, the United States government, which offered Poland a low-interest loan and lent considerable political pressure to the deal, will have beaten its European allies at a political contest that has lasted at least since 1999, when Poland became a member of the North Atlantic Treaty Organization.

Poland's bid to replace its Soviet-era fleet of MiG-21s and MiG-29s could mean $3.5 billion worth of orders for the manufacturer of the aircraft. But from the beginning, the contest has been cast as a largely political one, forcing Poland to choose between its alliance with NATO and its potential for membership in the European Union.

"It's been a pretty tough competition, not just for the manufacturers but for the countries involved. They've been playing a lot of politics in this," said Paul Nisbet, an aerospace analyst for JSA Research Inc. in Newport, R.I. "I'm sure the losers will all be saying that Poland didn't get the best product or the best price - that politics really made the difference."

High among the political demands of the competition was Poland's insistence that the plane's manufacturer make investments in the Polish economy that are at least equal to the value of the contract. All the potential builders pieced together a package of "off-sets" that called for forming alliances with Polish companies and building components in Polish factories.

Lockheed Martin Corp. claimed that its off-set proposal included more than 80 potential projects with more than $8 billion in economic value. The company would not provide details of its proposed deal.

While the competition to build Poland's fighter jets formally began after the country joined NATO, Lockheed Martin's interest in the deal dates back years further. A former vice president for strategy and planning for the company, Bruce P. Jackson, served as the head of a government-sanctioned committee in the mid-1990s that lobbied to bring Poland and other countries into the NATO alliance.

With more than 4,000 produced, the F-16 is one of the best-selling fighter planes in history and a workhorse in air forces around the world. The U.S. Air Force plans to replace its fleet of F-16s with the new F-35 Joint Strike Fighter under development, but Lockheed Martin continues to market and sell its F-16 overseas. The company plans to build about 60 of the fighters next year.

Built in Fort Worth, Texas, the F-16 has evolved through dozens of upgrades since it was first flown in 1976, and the version being offered to Poland scarcely resembles early U.S. Air Force models. Versions in use by the Air Force carry some of the most sophisticated weapons and surveillance systems in the American arsenal. Also, a "Block 60" version under development for the United Arab Emirates will be among the most sophisticated and deadly fighters ever built - generally superior to those in the American inventory.

Lockheed Martin says that the Polish "Block 52" aircraft would be the most advanced F-16 in Europe, matching the most capable multirole fighter jets in the NATO alliance.

The Mirage and Gripen also are regarded as quality fighter jets. But Charles Edelstenne, chief executive officer of Mirage manufacturer Dassault, said in an interview with the French radio station France Info yesterday that the plane's capabilities mattered little.

"The political element was the chief element, well beyond the quality or the price," Edelstenne said, according to Bloomberg News.

Lockheed Martin officials declined to comment about its prospects in Poland until the formal announcement today. "We have not been notified of anything yet," said Joseph Stout, director of communications for Lockheed Martin's aeronautics division.