Press Secretary Jody Powell said yesterday there is no contradiction between what President Carter said at a news conference on Jan. 12 and a statement the president gave Justic Department investigators the following week regarding a Pennsylvania congressman and the just-fired U.S. attorney in Philadephia.

The Justic Department has cleared Carter of any wrong doing in pressing for David W. Marston's speedy ouster at the urging of Rep. Joshua Eilberg (D-Pa.), who is under investigation by federal prosecutors in Philadephia.

In the unsworn statement last week, Carter said he has been told by an aide on Jan. 12, just minutes before holdings nationally televised news conference, that Eilberg was considered "of investigative interest."

During the news conference, Carter said, "As far as any investigation of members of Congress, however, I'm not familiar with that at all, and it was never mentioned to me."

Powell told reporters, "The president was told that Congressman Eilberg's name had come up in the course of another investigation, not an investigation of Congressman Eilberg."

Yesterday, presidential aide Robert S. Strauss conceded to reporters that the White House handling of the Marston affair was "not its finest hour."

But he strongly defended Attorney General Griffin B. Bell's firing of Marston, saying only that it should have been done "in the first 60 days, and then it wouldn't have come up" as an issue.

Strauss said that Marston had been insubordinate, and "while I don't have a quarrel with the boy, I would have fired" him. He said Marston didn't understand that Bell was his boss. "He was really in business for himself up there" in Philadelphia.

And House Speaker Thomas O'Neill, who earlier defended the decision to fire Marston, denounced him yesterday in surprisingly strong language.

"He never should have had the job. He is a Republican political animal," said O'Neill of Marston, who was administrative assistant (AA) to Pennsylvania Republican Sen. Richard Schweiker before being appointed U.S. Attorney.

"He went in there with viciousness in his heart and for only one reason, to get Democrats. I wonder what kind of an AA he was that Schweiker let him go," said O'Neill.