Despite increasing pressure to take more aggressive steps to keep troubled borrowers in their homes, the Obama administration said Wednesday that it had no immediate plans to alter its foreclosure-prevention program by increasing its reliance on reducing loan balances. The administration’s statement came as attorneys general and banking regulators in 14 states warned that policy makers needed to do more to stem the tide of foreclosures. The Obama program, announced in February as a cornerstone of the administration’s efforts to stabilize the housing market, has been running into increasing criticism as delinquencies have mounted.