Sen. William Proxmire (D-Wis.) said yesterday that budget directr Bert Lance should give up his job - not immediately, but soon - because Lance has neither the training nor the experience to run the Office of Management and Budget.

Proxmire, chairman of the Senate Banking, Housing and Urban Affairs Committee, was the only senator to vote against Lance's confirmation. Appearing on the Nation" (CBS, WTOP), Proxmire said Lance has "never had anything to do with budgets" and leaves the details of running OMB to his subordinates.

"In the one area where he is supposed to be an expert - running a bank - he hasn't done well," Proxmire said. He said the National Bank of Georgia, which Lance headed until he was appointed to his present position by President Carter, has been losing money.

Lance has been under heavy criticism and the subject of investigations recently for questionable banking practices he followed before he came to Washington. This criticism has centered on Lance's sizable bank overdrafts and his getting large personal loans from banks around the time he placed interest-free deposits from his own bank with them, a procedure called correspondent relationships.

A report issued 11 days ago by the comptroller of the currency cleared him of any criminal wrongdoing, but pointed out that the overdrafts were "unsafe and unsound banking practices." It said the series of personal loans "raises unresolved questions as to what constitues acceptable banking practices."

In another development. The New York Times reported in its Sunday editions that Lance may not have turned over to the Senate committee that approved his nomination a full statement of his assets and liabilities.

If ture, and Sen. Abraham A. Ribicoff's (D-Conn.) Governmental Affairs Committee is looking into it, this would appear to violate strong conflict-of-interest guidelines Carter issued in January for all Cabinet-level appointees. These guidelines require full disclosure of all assets and liabilities, those of immediate families and all other sources of income.

A spokesman for Lance, Robert W. Dietsch, said Lance made a full disclosure of his finances in accordance with Carter's guidelines.

Among the charges The Times made are:

That the financial details of a partnership consisting only of Lance and his wife, LaBelle, were not reported specifically on the joint net worth statement Lance provided the committee, even though the partnership, called Lancelot and Co., had substantial stock holdings and borrowed $1.2 million in the past three years.

That a $75,000 estimate Lance placed on the value of our partnerships he reported to the committee was "pulled out of the air," according to Thomas Mitchell, a Lance placed on the value of four partnerships he reported to the committee was "pulled out of the air," according to Thomas Mitchell, a Lance trustee appointed to make sure Lance avoided potential conflicts of interest. Mitchell later said the $75,000 figure was an estimate, not meant to be exact.

That another Lance partnership, L&M's Co., improperly deducted from its tax returns interest payments to banks that had made loans to the committee that ran Lance's unsuccessful campaign for the governorship of Georgia in 1974. Dietsch said he had no information on this, but whatever happened was "proper."

The Times also reported that Mitchell, as trustee for Lance, may have a conflict of interest because of his financial connections to Lance. Mitchell is a partner in L&M's Co., owns stock in the National Bank of Georgia and is a director of the Calhoun First National Bank - in which Lance has substantial holdings.

White House press secretary Jody Powell said of the charges: "It's my impression he (Lance) did meet the guidelines, which were in fact stricter for him than for any other official and which in every case were much more strict than anything required by law or ever required of federal officials."

Proximire, in the television interview called Lance "a man of integrity," but said he hopes "there will come a time when Mr. Lance will step aside." However, if Lance left now, Proxmire said, that would create the impression that he was "drummed out" because he lacks integrity.

But for all that, Proxmire said criticism should be directed not at Lance, but at Congress for approving his nomination and at Carter for making it. If Lance is to be criticized, Prosmire said, it should be for what he has done in office, not what he did before he got there.

"The confirmation process in the Senate must be brought up to date," Proxmire said. "We confirm many too many people.

He said many appointees "warm up" to senators personally and socially in advance of their confirmation hearings, and thus the questions are even if the Senate knew at the confirmation hearings what it knows now, it probably still would vote to confirm Lance.