By JUAN FORERO

CHIPIRIRI, Bolivia - In nearly 50 years of growing coca, José Torrico has seen army soldiers swarm across his fields to pull up his plants and heard threats from successive Bolivian governments determined to destroy his crop.

And like thousands of other coca farmers in this verdant, tropical region of central Bolivia, Mr. Torrico has refused to stop growing coca, the main ingredient in cocaine, even in the face of a relentless United States-financed effort to stamp it out.

Now, after years of persistence, he and his fellow farmers say they are eagerly anticipating the advent of a new era, one in which growing coca will finally be made legal. That is, they say, if Evo Morales is elected president on Dec. 18.

"It will be legalized," Mr. Torrico, 69, said with a broad smile as he showed off an orange nylon tarp loaded with freshly picked coca leaves. "This is good for us. Evo can do us favors."

Mr. Morales, a onetime leader of the coca growers federation, has steadily become revered by the left around Latin America as an unbending opponent of globalization. That is worrisome enough to the Bush administration. But more alarming to American officials is that a man who promotes coca farming - an industry central to cocaine production - may soon lead this Andean nation.

Rising in part on his pledge to legalize coca, Mr. Morales has become the top presidential candidate in Bolivia, and he now leads his closest adversary, Jorge Quiroga, an American-educated former president, by 33 to 27 percent, according to a poll conducted earlier this month.

Mr. Morales's ascent now, at a time when President Bush holds the lowest standing of any United States leader ever in Latin America, has intensified a clash of cultures with Washington that shows some of its deepest strains here.

For 20 years, Washington has sponsored efforts to eliminate coca as part of its fight against the illegal drug trade, and Bolivian governments have cooperated, eager for loans and other support from international lenders.

But today Washington-backed economic prescriptions are being rejected up and down the continent. And though the presidential race is tight, political analysts say that Mr. Morales may have the upper hand because of the potent anti-establishment fervor that has swept Bolivia, forcing out two presidents since 2003.

The growing appeal of Mr. Morales, who like most Bolivians is of Indian descent, runs deepest here in the Chapare, a New Jersey-size swath of rivers and thick jungle where coca cultivation has for years made Bolivia one of the world's top cocaine producers.

For thousands of years before that, however, Indian highlanders cultivated and chewed unprocessed coca to mitigate hunger and increase stamina. Though the Bolivian government has made growing coca largely illegal, the bright green leaves are taken for granted as part of Andean culture.

They are still bought and sold legally across Bolivia for chewing or making tea, with people young and old never giving it a second thought. Indeed, coca tea is sold in supermarkets and it is consumed across the Andes, even in elegant hotels and offices.

While acknowledging that cocaine trafficking is a problem, Mr. Morales and the coca growers contend that most coca in the Chapare goes for traditional uses. Mr. Morales says that as president he would allow the "industrial" use of coca, to make everything from toothpaste to pharmaceuticals to soft drinks to be exported as far away as China and Europe.

"Coca and coca tea can be industrialized to circulate internationally," Mr. Morales said during an interview en route to a meeting with coca farmers. "How can we not legalize, since we are not hurting anybody?"

Erecting road blockades and battling soldiers, the coca growers have already won victories against the Bolivian government once thought impossible, most recently with a pact last fall that allowed each farmer to plant up to a third of an acre with coca in the Chapare.

Today the blue, black and white flags of Mr. Morales's party, the Movement Toward Socialism, flutter from houses in the Chapare, and Mr. Morales is treated like a conquering hero during his frequent visits.

"Evo came up from the bottom, first as a union leader, then as the leader of the coca growers federation," René Arandia, a coca growers leader, said as he took a break from a recent meeting between Mr. Morales and several hundred cocaleros, as the growers are called, in the town of Lauca Ñ. "And now he's on his way to becoming president of the republic. For us, this is a victory."

For Washington, however, it is little short of a nightmare. American officials and leading drug policy experts contend that, no matter what Mr. Morales and the coca growers say, most of the coca grown in the Chapare winds up as cocaine.

They also say that the recent pact permitting limited coca production in the Chapare has emboldened not only coca farmers, but cocaine traffickers.

"The results are pretty clear," said Eduardo Gamarra, the Bolivian-born director of Latin American studies at Florida International University, who has closely tracked the drug trade. "Coca production has expanded considerably in Bolivia, and cocaine production has expanded considerably in Bolivia."

The United Nations said in a recent report that Bolivia produced up to 107 tons of cocaine last year, up 35 percent from 2003. The sudden increase has prompted warnings that cocaine traffickers are gaining ground after several years in which Bolivia's drug crops were substantially reduced.

"I don't think there's an attractive or viable future by becoming a narco-state," John Walters, the White House drug czar, said in an interview.

American officials, though, have watched helplessly as Mr. Morales's influence has grown. When they have offered opinions - like claims, with little proof, that Mr. Morales is linked to drug trafficking - it has only strengthened Mr. Morales's appeal.

"They accuse me of everything," Mr. Morales told a crowd on a recent campaign swing. "They say Evo is a drug trafficker, that Evo is a narco-terrorist. They don't know how to defend their position, so they attack us."

As president of the so-called Six Federations, a confederation of coca growers, he molded it into a powerful political force that propelled him to Congress.

Mr. Morales is well aware of the debt he owes his base. "If not for the Chapare, if not for the Six Federations," he says, "there would not be an Evo Morales."

Though 20,848 acres of coca was uprooted in eradication efforts in 2004, farmers keep planting it. They say they have no choice but to grow coca, since other crops fare poorly here and American-financed efforts to encourage them to switch to legal crops have stumbled.

Mr. Torrico's 20 acres are filled with crops like bananas, fruit, yucca, coffee and cacao. On a tour of his plot, though, he listed off the hurdles he faces making ends meet, from high transportation costs to bottom-basement prices for most of his crops.

Coca, on the other hand, earns him as much as $162 dollars a month. It is not a windfall, even by Bolivian standards, but it is a living, he said.

"With coca, I was able to send my children to study," said Mr. Torrico, who has eight children. "The other stuff, the citrus fruit, the bananas, give us nothing. Coca is what sustains us here."