Washington ? A key senator postponed action Thursday on a homeowner rescue package that could help half a million strapped borrowers get government-backed mortgages, as negotiators inched toward a bipartisan deal.

The delay on the action until next week clouded the prospects of an emerging compromise between Sen. Christopher J. Dodd, D-Conn., the Banking Committee Chairman, and Sen. Richard C. Shelby of Alabama, the panel’s senior Republican. It also highlighted the tricky political calculations involved in reaching a bipartisan housing deal in an election year when the two parties are competing intensely to appeal to voters who cite the economy as their top concern.

Dodd and Shelby said Thursday that they were near agreement, but after hours of stop-and-start haggling, particularly over how to pay for the plan, Dodd canceled a committee session to vote on the measure. Also at issue was how tightly to regulate government-sponsored mortgage giants Fannie Mae and Freddie Mac.

“It is my desire that we fashion legislation that will enjoy broad-based support. It may not be possible in the end,” Dodd said. “If it doesn’t happen, so be it, but we’re not going to have it not happen because we didn’t try.”

The stalemate comes as more U.S. homeowners are falling behind on mortgage payments.

Nationwide, 243,353 homes received at least one foreclosure-related filing in April, up 65 percent from 147,708 in the same month last year and up 4 percent since March, RealtyTrac Inc. said.

Nevada, Arizona, California and Florida were among the hardest hit states, with metropolitan areas in California and Florida accounting for nine of the top 10 areas with the highest rate of foreclosure, the company said.

Irvine, Calif.-based RealtyTrac monitors default notices, auction sale notices and bank repossessions.

One in every 519 U.S. households received a foreclosure filing in April. Foreclosure filings increased from a year earlier in all but eight states.