Ex-Postmaster General May Head RTC : * Thrifts: Albert V. Casey is said to be the top choice to succeed L. William Seidman at the S&L; bailout agency.

Albert V. Casey, former chairman of American Airlines and onetime postmaster general, has emerged as the prime candidate to become chairman of the Resolution Trust Corp., the agency charged with administering the thrift industry bailout, officials said Wednesday.

Casey, 71, would succeed L. William Seidman, who is retiring as head of both the Federal Deposit Insurance Corp. and the 2-year-old RTC, which is staffed and managed by the FDIC. A formal announcement is expected this month.

Seidman, who is on a search committee that the Administration set up to help find his successor, said Casey is “the leading candidate” among several who have been considered.

Administration officials said the White House decided to bring in a high-profile business executive to take over the S&L; cleanup and the sell-off of billions of dollars worth of real estate and other assets that the government seized from failed thrifts.

While Seidman was chairman of the RTC, he often had to spend much of his time at the FDIC, which has become increasingly embroiled in the rescue of insolvent banks. As a result, the day-to-day management of the RTC was handled by career bureaucrats on loan from the FDIC.

The Administration hopes that by giving the new chairman broad powers over the RTC, he will be able to deal more effectively with Congress and the thrift and real estate industries.

But if Casey takes the position, he is likely to face some political difficulties. Congress is up in arms over charges that the RTC has been poorly managed, and Democrats have been criticizing the Administration for failing to come to grips with the S&L; crisis.

This fall, the Administration is asking Congress for another $80 billion to rescue still more failed thrifts, bringing the cost of the bailout to $160 billion, not counting interest. But two independent agencies warned this week that the total price tag could go much higher.

In addition, critics have complained that the scope and powers of the new RTC chief executive have not been well-defined.

The Administration believes that Casey can be given expanded powers without a broad restructuring of the RTC, but congressional leaders are drawing up separate plans to overhaul both the agency and its management.

Meanwhile, Seidman has asked Congress to separate the RTC completely from the FDIC, which would allow dozens of managers on loan to the RTC to return to the FDIC. The White House opposes the Seidman plan, however.

Casey is a former president of The Times Mirror Co., owner of The Los Angeles Times. He also was a former president and chairman of American Airlines, and in 1986 was postmaster general. Federal regulators brought him in to run FirstRepublic Bancorp just before it failed and was seized in 1989.