The man negotiating to buy the Baltimore Orioles is a political and financial gadfly with a reputation for playing hardball in his personal dealings.

William E. Simon, former Treasury secretary and onetime Wall Street investment counselor, has parlayed his fame as a Ford administration official into a series of business ventures ranging from politics to publishing.

He has struck out in a few of them -- in part because of his strong political leanings and his sometimes vehement temper. In the process, he has become a darling of right-wing Republicans.

Ironically, it was Simon who as Treasury secretary first proposed legislation to limit the use of professional sports teams as tax shelters. Congress adopted Simon's plan in 1976.

An often glib and sometimes charming man, Simon came into national prominence as federal energy administrator in the Nixon administration, where he ran the White House rationing program during the 1973 Arab oil embargo.

When George P. Shultz left office as Treasury secretary, Nixon appointed Simon, who had served as that department's number two man. The former New York City bond salesman stayed on in the Ford administration, through 1976.

It was during his tenure as Treasury secretary that Simon's political ambitions took hold -- and his stock among conservatives began rising.

The Treasury chief became known as the administration's chief spokesman for bigger business tax writeoffs, lower government spending and balanced budgets -- even during the 1974-75 recession.

His rhetoric eventually embarrassed other key Ford administration policymakers, but it won him fans among archconservatives. Today, Simon often makes himself heard on a variety of political issues.

The incongruous last act as secretary by this ardent foe of big spending was to tour Moscow and London on a $131,500 trip with a party of 42, among them his wife, two sons and the wives of four aides.

He acquired a reputation for a quick temper. At Treasury, Simon often chewed out aides unmercifully, several times firing his dining-room steward for relatively minor infractions. Morale in the department plunged.

Simon once angered a New Jersey judge by berating the court for refusing to allow him to keep a Tommy gun he was given as a gift. (Possession of a submachine gun by a private citizen technically is illegal in the United States.)

And he fought with the State Department over whether the law allowed him to keep a number of expensive presents he received during his term as Treasury secretary -- including a Soviet shotgun. (The State Department said no.)

Since leaving the Treasury, Simon has flitted among a series of new ventures.

He briefly toyed with the idea of running for governor of New Jersey, but scrapped the notion after political analysts judged him unlikely to win the necessary backing.

He served as board chairman of the now defunct New York Trib, but left abruptly after a dispute in which the paper's publisher charged he was trying to influence editorial content.

He wrote a book, "A Time for Truth," which has served as something of an economic and social manifesto among some conservatives.

As far as is known, buying the Baltimore Orioles would mark Simon's first entry into organized sports -- at least away from the political arena. And there is little doubt he would become directly involved in the team. The asking price reportedly is $12 million.

Not much is known about Simon's interest in buying the team. There have been rumors he might seek to move it to New Jersey, where he is said to continue to harbor political ambitions. The team's lease expires in Baltimore after the 1979 season; reportedly, he might be interested in having the team play 11 games at RFK Stadium in 1979 and more thereafter.