After 2 1/2 weeks of testimony and several major setbacks, the prosecution has rested its case against former representative Otto E. Passman (D-La.) in the bribery and tax evasion trial taking place in Passman's home town.

Passman, 78, was indicted a year ago on charges of receiving more than $200,000 from Tongsum Park, the millionaire South Korean businessman, in return for pressuring the U.S. and Korean governments into rice sales beneficial to Park. A second indictment charged Passman with failure to pay taxes on the alleged payoffs.

Government prosecutors called 19 witnesses in an attempt to show that Passman, abusing his powerful House appropriations subcommittee chairmanship, took $213,000 in bribes and payments from Park as part of an alleged conspiracy that earned Park over $8.5 million.

Justice Department prosecutors David Scott and Morris Silverstein experienced difficulty in presenting the case, beginning with Park's testimony.

Park, who was on the stand for a week, testified about taking brown manila envelopes full of cash to Passman in the congressman's Washington office. However, Park's memory on the details of payments was vague, and at one point his testimony on two of the bribery counts differed significantly from the indictment.

In order to make its case, the prosecution coupled Park's testimony with his two diaries and ledger, which recounted meetings with Passman, and notations, often in code, of payments to him.

In a lengthy cross-examination, however, Camille F. Gravel Jr., Passman's attorney, attacked the credibility of Park's records.

The prosecution's next most important witness, former representative Richard T. Hanna (D-Calif.), now serving a 16-month sentence for his involvement with Park, was not allowed to testify.

The government had planned to have Hanna corroborate Park's ledger by indicating which payments in the ledger he received from Park.But U.S. District Court Judge Earl Veron sustained a defense objection to Hanna's testimony on the ledger.

Veron ruled Tuesday that the prosecution could not show the jury a chart summarizing Park's alleged payments to Passman.

Louisiana Gov. Edwin Edwards appeared earlier this week, testifiying that he introduced Passman and Park in 1970 to further his desire to sell Louisiana's rice reserves.

In a surprise move during cross examination, Edwards told defense lawyer Gravel, on leave from the governor's staff, that Park said in 1976 that there were no contributions made to Passman.

Edwards, who received $20 000 from Park during his 1972 gubernatorial bid, testified that he asked Park "especificially if he had any similar dealings with Congressman Passman" during a visit to the Superdome in 1976. Edwards said Park responded that "he wouldn't dare offer" a contribution to Passman.

Asked why he had not told the government about the conversation earlier, Edwards replied, "you never asked me."

Although the prosecutors would not comment on the progress of the trial, one observer noted that the case had "built-in" problems, one of them being Tongsun Park's testimony, which has been disputed in the past.

Hanna, in an interviewed, said that when he pleaded guilty to a conspiracy count last year "everyone was expecting a whole string of indictments," but after watching the Passman trial he feels foolish for not having gone to trial.

Testimony in the Passman trial resumed this afternoon when the defense opened its presentation. Gravel promised to have the case before the jury next week.