Respected Washington newsman Jim Wieghart is in line to become Sen. Edward Kennedy's new chief of staff. For the time being, the former editor of the New York Daily News will serve as one of the senator's deputy chiefs of staff and as director of communications. The other deputy chief of staff is Ranny Cooper. Sources on Capitol Hill say, however, that Wieghart will eventually replace the present staff director, Lawrence Horowitz, who has been with Kennedy for a number of years and who is considering two offers to go into investment banking. Horowitz said yesterday that he will leave the staff in the summer. Wieghart, a former Milwaukee Journal and Milwaukee Sentinel reporter, has worked on the Hill before. He worked briefly for Sen. William Proxmire and former representative Henry Royce, both of Wisconsin.

After leaving the Hill, Weighart was Washington bureau chief of the New York Daily News and later became the tabloid's editor. He left there when James Hoge took over as publisher two years ago and since that time has been writing three political columns a week for Scripps-Howard out of the Washington bureau. Because it's a staff change in Kennedy's office, the speculation, as ever, turns to what this means to the senator's political ambitions. Wieghart, who begins his new job Monday, said that while Kennedy's decision not to seek the Democratic Party's nomination in 1988 is a firm one, "Kennedy is always prepared to run for the presidency if the opportunity presents itself. He would like to be president someday. I hope he can," Wieghart said, "which is one reason I'm going to work for him."

Horowitz, who is a medical doctor, has worked for Kennedy for 16 years. He was staff director of the health subcommittee of the Labor and Human Resources Committee and has been on the senator's personal staff since 1981. A Mural for the Challenger 7

Of all the memorials planned for the space shuttle Challenger, one of the more lasting ones may result from a proposal made yesterday to hang a painting in a Capitol corridor. It would be designed for a blank space left more than a century ago by the Italian painter Constantino Brumidi for future generations to honor their heroes. Senate Majority Leader Robert Dole said, "I can't think of a better place for this memorial to our space heroes," noting that the space immediately across the corridor shows a 1970 painting of the manned Apollo landing on the moon in 1969.

Dole made the proposal jointly with Senate Minority Leader Robert Byrd. They estimated the memorial would cost $20,000 and predicted the money could be raised privately. Sen. John Glenn, the former astronaut and the first American to orbit the Earth, said he would like the last message sent by Challenger before it exploded Jan. 28 to be part of the painting. "I hope that the words 'Go at throttle up' can find their way into this mural. They are far more than just a courageous epitaph. They are America's history and America's destiny. And they will turn tragedy into triumph once again." End Notes

Washington lawyer and businessman Mike Feldman, who now lives both in Palm Beach, Fla., and Washington, is planning to buy five radio stations in cities ranging from New Mexico to Florida. Feldman, who was counsel to President John F. Kennedy, recently sold his interest in National Savings and Trust bank and in WLLH, a radio station in Lawrence/Lowell, Mass. . . .

Grammy-winning singer Jennifer Holliday recently toured the campus of Howard University, where she is considering enrolling next year. Owen Nichols, vice president for administration and secretary of Howard, said Holliday is interested in the school's program designed for people who do not have time to attend classes on a day-to-day basis. He said Holliday plans to major in English, with a concentration on black literature . . .

The battle for the hearts and minds of the Library of Congress continues. Russell Mokhiber, organizer of the "Books, Not Bombs" campaign to protest Sunday closings and cutbacks in evening hours, said that on Monday Jesse Jackson, the man of many protest movements, will join the protesters in the main reading room. Maybe he'll even be arrested. Mokhiber hopes authors and leaders who have been contacted will come and join the movement in a protest similar to the one at the South African Embassy . . .