Sen. William Proxmire (D-Wis.), chairman of the Senate Banking Committee, has written to President Carter asking him to reappoint John R. Evans to the Securities and Exchange Commission.

It was his third letter on behalf of Evans, whose term as commissioner expired eight months ago.

In another recent criticism of the personnel policies, Proxmire said in congressional remarks that his committee "has been waiting for nominations by the White House for 20 vacancies that require Senate confirmation."

The vacancies, according to Proxmire, include one seat each on the Federal Home Loan Bank Board and the SEC, two seats on the Federal Reserve Board, three seats on the new National Credit Union Administration Board, and the 13 members of the Board of directors of the National Consumer Cooperative Bank.

Arnie Miller, director of the Office of Presidential Personnel, said of Proxmire's criticism: "Some of those are cheap shots because (the criticism) refers to new positions. We are preparing recommendations. We don't want to move precipitously."

About Evans, he said, "We are still reviewing candidates for the position, and Evans is among them."

On the Evans reappointment, Proxmire wrote, "The long delay in filling his seat has created great uncertainty at the commission, which has several important issues awaiting action."

Proxmire also said, "It is personally unfair to Mr. Evans, who needs to be able to make plans for the future."

The Proxmire letter received a bipartisan backing with the ranking minority member of the committee, conservative Jake Garn (R-Utah), cosigning.

Some powerful members of the securities industry have opposed Evans' reappointment. They want the Republican seat on a five-person commission filled by someone from the industry.

The White House has considered a number of industry candidates, but apparently the administration has not found one to its liking.