The Obama administration recently invested more than $1 billion from the stimulus and the healthcare law into the National Health Services Corps to beef up doctor recruitment. It's more money than the 40-year-old agency has ever had. Nearly 5,000 recent medical school graduates accepted federal grants to pay off tuition and school loans averaging $150,000 per student. The awards come with contracts that obligate the young doctors to remain in what are typically rural areas for three to five years. The corps hopes to recruit another 2,800 students next year. A report by the corps' advisory council estimated that 27,000 primary care physicians are needed to meet the needs of about 45 million Americans in medically underserved areas. But several young doctors who were interviewed said they are struggling with whether to spend a career in rural settings. Experts said they expect retention to be a problem.