NEW YORK (AP) _ AT&T Corp. laid the groundwork for its breakup into three companies by offering buyouts to 77,800 managers Wednesday if they leave by the end of the year.

If they decline the offer, they risk being fired next year and receiving a less-generous severance package. The company did not estimate how many people would accept.

``We felt the sooner we gave people the financial considerations, it would give them more time to mull over the psychological and emotional side to this,'' AT&T spokesman Burke Stinson said.

AT&T has not said how many of its 302,000 employees will be needed by the three companies that result from the breakup. The Wall Street Journal, citing anonymous sources, has reported that 20,000 may be cut.

AT&T announced in September that it is breaking up into a communications services company, a communications equipment manufacturing company and a computer company.

The managers who received the severance offer represent half of the company's supervisory staff. The other half has been promised jobs after the breakup, Stinson said.

AT&T's 150,000 or so non-management employees may also be affected by job reductions after corporate leaders decide in mid-January how many people are needed. Most of those employees are covered by union contracts that, in some cases, call for severance payouts far larger than those given to managers.

The managers were offered up to 35 weeks of salary, depending on length of service with the company, a bonus of 20 percent of that lump sum and eight weeks of severance. People who are cut in January will not be offered the eight-week severance pay.

If unionized workers are eventually cut, some will be entitled to 104 weeks of salary.

The managers have until Dec. 29 to decide whether to accept the buyout package.

Regardless of whether they accept the offer or are dismissed, they will get health benefits for a year and $10,000 for retraining and relocation.

``At this point we can't tell you how many people will be required to operate the new AT&T and the new equipment company because we don't know yet,'' AT&T chairman Robert Allen told employees Tuesday.

Since the breakup of the Bell System in 1984, AT&T's workforce has dropped from 373,000, virtually all in the United States, to 302,000, including 50,000 who work overseas.