WASHINGTON — President Barack Obama's administration is considering spending taxpayer dollars to cut monthly payments for homeowners on the verge of foreclosure, according to two people briefed on the proposals. The deliberations came as lawmakers prepared to enact a new tax credit of up to $8,000 for first-time homebuyers that is intended to boost the ailing housing market. Details of the plans to aid troubled borrowers were not final but were expected to be unveiled in the coming weeks, according to the people who declined to be identified because the details were not yet complete.