RUNNING for the presidency of the United States seems easy enough - if you know nothing about the game of politics. Take, for example, the case of Paul Laxalt who is currently listed as a ``possible'' candidate for the Republican nomination. Several Republicans among President Ronald Reagan's friends and long-time supporters are urging him to run. He was an early pro-Reagan enthusiast. He is a personal friend of Mr. Reagan. He reflects and represents the political point of view of Mr. Reagan. Of all possible Republican candidates he would probably be the one most likely to push on along the Reagan road.
But there is an important date on the Laxalt calendar which can determine whether he would be a viable candidate. As presently scheduled June 29 is the opening day for a court trial which he initiated.
Mr. Laxalt is a former governor of Nevada and former senator from Nevada. He was first elected to the Senate in 1974. He was reelected in 1980. He stepped aside in 1986 presumably so that he could more easily run for the presidency, along with his former Senate colleague Howard Baker of Tennessee. The two might have trodden the same path through the primaries down to the convention in 1988, but in March events took a sudden turn which separated them.
The Tower Commission report undermined the tenure of Donald Regan as chief of staff at the White House. The President offered the post to Mr. Laxalt, who declined. He then offered it to Howard Baker, who accepted. Ever since the name and face of Howard Baker have become familiar to Americans who watch the evening television news programs. He rivals Republican Senate leader Robert Dole of Kansas in time on the air.
Mr. Laxalt has meanwhile been back in Nevada getting ready for June 29.
Three years ago, in September 1984, he filed suit for libel against the McClatchy newspapers of California. He alleged that those newspapers had published articles ``permeated with actual malice, perversions of truth, and conscious falsehood.'' He said they were ``defamatory'' and he asked the court for $250 million in damages.
The article dealt with a four-year period between Mr. Laxalt's tenure as governor and his election to the Senate. During that time, according to his biography printed in the 1986 edition of the Congressional Directory, he was ``involved with family and associates in construction and opening of Ormsby House, a hotel-casino in Carson City.''
The articles published in the McClatchy newspapers alleged that ``skimming'' was practiced at the Ormsby House. Skimming means skimming off some of the profits before taxes. The articles alleged that the practice had been uncovered by the Internal Revenue Service and that Senator Laxalt had used political influence to head off prosecution.
A lot of politics can depend on what happens next. Laxalt friends say he thinks he will come clean out of the trial and be ready to launch his campaign for the presidency. It is said that many conservative Republicans who are now tentatively backing Congressman Jack Kemp of New York will swing over and back Laxalt.
If that happens the race for the Republican nomination will presumably settle down into a three-cornered affair between Vice-president George Bush, Senator Dole, and former Senator Laxalt. If it doesn't happen Kemp will presumably continue to be the candidate of the hard-core conservatives while most of the party will move in behind Bush or Dole.
In either case the choice for the Republicans will presumably be between a person in the Reagan political image (Kemp or Laxalt), a pragmatist of the center (Dole), or Bush who was regarded as a moderate and a liberal until his political identity was swallowed into the Reagan White House.
But then on the sidelines there is Howard Baker busy at keeping the White House running efficiently.
One can't help wondering whether Mr. Laxalt sometimes wishes he had taken that chief of staff job at the White House.