A federal judge ruled yesterday that former representative Daniel J. Flood (D-Pa.) is mentally competent to stand trial a second time on conspiracy, bribery and perjury charges.

U.S. District Court Judge Oliver Gasch, in a 17-page opinion said that while there has been a "marked deterioration" in Flood's mental ability, he is able to assist his lawyers in preparation of his defense, Flood, 76 resigned from Congress Jan. 31.

Flood's retrial is scheduled Feb. 25. However, this week, Flood's lawyers, Axel Kleiboemer and Walter H. Fleischer, asked for a postponment until early May. Otherwise, the lawyers said in court papers, they will have to withdraw from the case because they will not have adequate time to prepare for trial. Gasch has not ruled on the request.

During a lengthy competency hearing in federal court last month, Flood's lawyers had attempted to persaude Gasch their client's mental capacities are so weakened that he does not understand the charges and is unable to assist his lawyers.

In ruling yesterday, however, Gasch said he agreed with a court-appointed psychiatrist who concluded it would be "difficult but not impossible" for Flood to participate in what is expected to be a protracted trial.

Dr. George Weickhardt, who examined Flood five times, testified the former representative experiences memory problems, fatigue and has a short attention span. Gasch noted, however, the pyschiatrist's evaluation said that "with rest and encouragement" Flood's memory and attention improves.

Moreover, when Flood took the witness stand almost five hours during the hearing, Gasch said, the expert observed that Flood was "emphatic, animated, exhibited the will to fight back and the ability to be an effective witness on his own behalf."

Flood, once one of the most powerful members of Congress, is charged with taking more than $50,000 in bribes from businessmen for his influence as chairman of a House Appropriations subcommittee. Flood's first trial a year ago ended with hung jury.

Gasch noted that during lengthy cross-examination at the competency hearing, Flood vigorously denied he had violated any laws or accepted payments for service as the government alleges.

Gasch said Flood "exhibited adequate ability to cope with the charges and his credibility, unlike that of most of the witnesses against him, is unimpared."

At one point during the competency hearing Gasch remarked that if Flood defended himself at trial with the vigor he showed during the hearing, he would be acquitted of the criminal charges.

Since his first trial last February, Flood has been hospitalized for a variety of ailments, and has undergone gall bladder and eye surgery. Gasch said, however that a trial conducted "under flexible conditions" would not jeopardized Flood's health.