Columnist May Challenge Bush for Nomination : Politics: A Patrick Buchanan candidacy could open the President to attacks from the disgruntled right. White House discounts problem.

Conservative columnist Patrick J. Buchanan is said to be preparing to challenge President Bush for the 1992 Republican presidential nomination in a candidacy that could jeopardize White House plans for a low-profile primary election campaign.

The most direct result of a Buchanan candidacy, Republican political operatives said, would be to force Bush to enter the field sooner than he planned, to contest what could be wounding charges from a disgruntled right.

The indication that Buchanan is thinking seriously about running against the President offered yet another sign of the erosion in Bush’s political strength that already has given Democrats hope that he is vulnerable.

“I don’t have any doubt in my mind that he’s going to run,” long-time Republican operative Edward J. Rollins said of Buchanan, a 53-year-old former aide to Presidents Ronald Reagan and Richard M. Nixon. “Pat has basically decided to do it, and I think we’ll get the final word sometime around Thanksgiving.”

Pennsylvania voters last week brought a state of high anxiety to the White House when they rejected former GOP Atty. Gen. Dick Thornburgh in what had once been regarded as a shoo-in Senate race.

With Bush already forced to compromise with the Democrats on unemployment benefits and civil rights, having to defend his right flank could complicate the task of those senior advisers seeking to shore up his public image.

But some Republican sources suggested that the President ultimately might benefit by appearing as the moderate between a conservative and the Democrats. And Bush, when asked about a Buchanan candidacy, insisted, “I haven’t paid much attention to that yet.”

“I don’t think we’re taking it very seriously at all,” a White House official said later.

Buchanan was said by associates to be out of town and did not return messages left on his telephone answering machine. But, after the Manchester, N.H., Union Leader last Friday urged in a front-page editorial, “Run, Pat, run!” Buchanan was quoted in the paper as saying, “I will consider it.”

Buchanan’s sister, former U.S. Treasurer Angela Buchanan, was quoted by two sources Thursday as saying: “It’s a go.”

Any Republican would have a difficult time taking his party’s nomination from Bush. But a Buchanan candidacy could force a sharp change in White House plans to remain above the fray while Democrats waged self-destructive primary election campaigns.

With Buchanan in the race, Republican operatives said, Bush would have little choice but to go head to head with the conservative columnist who, in syndicated newspaper columns and regular TV appearances, has been one of the President’s severest critics.

“I will support Bush as I did in the 1988 campaign,” conservative consultant Craig Shirley said. “But, if Pat does run, I hope they (the President and his advisers) take him seriously--for Bush’s sake.”

Buchanan, who appears regularly on television’s “Crossfire” and “The McLaughlin Group,” advocates a rigid America-first agenda that some have called isolationist. He is a staunch opponent of abortion and foreign aid; and, in a recent column, he called for the abolition of the federal income tax.