Vice President Biden is not for adding troops to Afghanistan. That's good. He is reported to be the leading 'dove" in the White House. However, his thinking that training Afghan troops to replace US troops will do the trick is also not going to work: -
..."Mr. Biden does not favor abandoning Afghanistan, but his approach would reject the additional troops sought by Gen. Stanley A. McChrystal and leave the American force in Afghanistan roughly the same, 68,000 troops. Rather than emphasize protecting the Afghan population, he would accelerate training of Afghans to take over the fight while hunting Al Qaeda in Pakistan using drones and special forces. His view has caught on with many liberals in his party"... NY Times Oct 14, 2009.
That too will fail for the same reasons Vietnamization of South Vietnamese to fight the Vietcongs didn't work. The local troops knew they would be supporting a regime in their own capital the people despised. Then and now, the morale is not there. The incentive is not there.