Breaking news from the Land of the Pundits: Norman J. Ornstein, the American Enterprise Institute political expert and leading quotemeister for much of the last decade, has been dethroned. The new king is Thomas E. Mann, director of governmental studies at the Brookings Institution. AEI scholar William Schneider will hold down third place.

Ornstein, cited everywhere for his views on almost everything, was dubbed the "King of Quotes" in 1986 by the Washington Monthly. And that was when he was mentioned in newspapers and magazines only 151 times. His highness continued his reign over the years, peaking in 1994 with 389 mentions in newspapers and magazines, according to an exhaustive Nexis database study out today in the estimable National Journal.

Part of the reason for his decline may be the spread of a "no-Norm rule" at some magazines and newspapers because of his ubiquitous presence in the media. The Wall Street Journal is said to have had one, so has the Los Angeles Times.

The reason for the rules, and the difficulty in enforcing them, as one journalist pointed out, is "Norm's so very good; he really is." He returns calls quickly and delivers the cogent quote. Some papers, once addicted, can't give him up.

Good as he is, his numbers have dropped dramatically of late, enabling Mann to surpass him. "Mann's lead is no fluke," the Journal said. "He has made great strides since 1989, when Ornstein had more than twice as many Nexis mentions."

And it turns out that Mann actually overtook Ornstein in 1993, the study showed, when Ornstein was having trouble with his split-finger fast quote, before falling behind again in 1994.

For the 12-month period ending April 30, Mann was quoted 277 times to Ornstein's 251 pearls of wisdom, with Schneider at 191. But the crown clearly sits uneasy. In the last four months, Ornstein has been slightly ahead of Mann. Calling for a Recount

A not-very-happy AT&T spokesman called to demand a correction to an item Wednesday that said AT&T Chairman Robert Allen pocketed $16 million in compensation in a year when he sacked 40,000 employees.

WRONG, FALSE on both counts. Allen only got $5.2 million in cash and options, and the rest is long-term stock options that assume the stock performs well.

What's more, there are going to be only about 18,000 layoffs over the next three years, the spokesman said, the rest of the job reductions will come from attrition and buyouts over three years.

What can we say? Sometimes it's hard to count so much money and so many bodies. New Faces at USTR

The new team at the U.S. Trade Representative's office seems to be falling into place. Word is that Margaret C. Sullivan, former longtime Hill aide and now special assistant to Defense Secretary William J. Perry, is the leading candidate to be chief of staff to Charlene Barshefsky, the acting head of the office and nominee for the top spot.

Also, Jay Ziegler, a Clinton campaign operative who's now special assistant to Interior Secretary Bruce Babbitt and before that deputy director of the office of communications there, is said to be the pick to run Barshefsky's press operation.

They'll be replacing some of the crew Commerce Secretary Mickey Kantor took with him when he left the trade job. Meanwhile, at Commerce, Clyde Robinson Jr., a deputy assistant secretary for trade development whose dad is an ABC-TV cameraman at the White House, is moving to be deputy chief of staff for external affairs, handling scheduling, foreign trips and such. David Marchick, an aide to Kantor at USTR, is coming over to replace Robinson. And LeeAnn Inadomi, is leaving the White House office of Cabinet affairs to work in Kantor's office as senior adviser to chief of staff Peter L. Scher. Family Time

White House aide John Emerson, who headed the successful effort for the Clintonites on the GATT treaty, is heading the interagency effort to get most-favored-nation status for China. Clinton is to formally announce his decision June 3 granting the Chinese that continued status, and then Congress has 90 days, or until early September, to reject it. That will give Emerson plenty of time to deal with the twin girls he and his wife, Kimberly Marteau, now top spinmeister at the U.S. Information Agency, are expecting this fall. Moving up at OPM

At the Office of Personnel Management, Janice R. Lachance, formerly director of communications, has moved up to chief of staff to Director James B. King. Deputy communications boss Rosalie A. Cameron moves up a notch and Bruce Milhans, who handled press for Senate Minority Leader Thomas A. Daschle (D-S.D.), take's Cameron's deputyship. Ambassadors Named

Catching up with recent action on the ambassadorial front, President Clinton has named several career foreign service officers to ambassadorships in Africa.

Stanley Schrager, the counsel for public affairs at the U.S. Embassy in Port-au-Prince, Haiti, was named ambassador to Djibouti; John Hicks, assistant administrator for the U.S. Agency for International Development, is to run the embassy in Eritrea; Alan McKee, now consul general in Johannesburg, was tapped to be ambassador to Swaziland and Arlene Render, former director of central African affairs at the State Department, is headed for Zambia.

Harold Geisel, former acting inspector general at State who was named ambassador to Mauritius and the Comoros Islands in March, will also be ambassador to the Seychelles.