President Barack Obama plans to veto a bill whose opponents say would make it harder for homeowners to stop foreclosures.

The move marks the Obama administration's most direct intervention so far into a growing debacle tied to how banks foreclose on homes, and the first effective veto of Mr. Obama's presidency. The veto could make it more difficult for banks to complete paperwork and speed the foreclosure process, and could give homeowners more time to rework loans.

Several...