SAN JOSE MINE, Chile - Drillers neared the lower reaches of a gold and copper mine where 33 men have been trapped for more than two months, preparing Friday for a breakthrough that would unleash a national outpouring of joy.

Engineers were carving through the last 128 feet (39 metres) of rock, taking care to keep the T130 drill from jamming or punching through with too much force, Mining Minister Laurence Golborne said.

"We are very close," Golborne said. "It would be very complicated if after all the work we have done ... you lose the hole. We have to be very careful and do it in a controlled way."

The "Plan B" drill was poised to win a three-way race to reach the miners with a hole wide enough to accommodate their escape capsule. Two other drills, "Plan A" and "Plan C," had to slow down after repeatedly veering off course.

The breakthrough -- to be heralded with a loud siren -- was sure to be an emotional milestone in the tent city known as "Camp Hope." Expectations soared as word came that Chile's first lady, Cecilia Morel, would meet with the families.

"There's just a little bit left to go, a very little bit," said Cristina Nunez, anxious to see her husband, Claudio Yanez, and shivering in the bitter cold of the desert morning.

If the shaft's rock walls are found to be strong, the miners could be pulled out beginning Tuesday. If not, rescuers will line the shaft at least partially with steel pipe, delaying the rescue for three to eight more days.

Nunez is among those who want rescuers to take no chances, and wait a few more days if necessary to pull them all out safely.

The T130 drill aimed at a workshop 2,047 feet (624 metres) below ground.

That's not as deep as where the miners happened to be gathered together, eating their midday meal, when 700,000 tons of rock collapsed Aug. 5. The mine runs like a corkscrew for more than four miles (7 kilometres) below a rocky hill in Chile's vast northern Atacama desert, and at any other time, some would probably have been crushed in the middle section.

Once the drilling is complete, a video camera will be lowered through the shaft, and the decision on whether or not to line the shaft will be made Saturday, Golborne said.

Both alternatives -- going without a liner or putting in steel pipe -- risk a disastrous setback, he said: "It's not a technical piece of cake."

President Sebastian Pinera announced that Bolivian President Evo Morales would join him for the rescue. One of the trapped miners is Bolivian.

The actual rescue is expected to take 48 hours as the miners are pulled out one by one, a made-for-TV spectacle that has drawn nearly 800 journalists to this isolated spot in the desert.

Chileans have rallied around this spare-no-expense rescue effort, and Pinera has surged in popularity for his close management of the crisis.

"What started as a tragedy should end as a great blessing," he said, praising the rescue effort for strengthening Chileans' spirits.

He also said his administration "has acted as a government must in these kinds of situations," taking on complete responsibility once it became clear that the San Esteban mining company was incapable of handling the rescue. "And just as I said on that first day, we would do everything humanly possible to pull them out alive."

Sen. Isabel Allende said that "the battle isn't over," however.

"Chile is a country that is able to confront its challenges, but on the other hand it is a country that still has a long way to go," said Allende, the daughter of President Salvador Allende. "We must keep working for safety in the mines."