Senator McCain filed papers yesterday with the Federal Election Commission to establish the John McCain for President Exploratory Committee.
The 62-year-old senator is known in America as a moderate within the increasingly conservative party, and for that reason may have problems finding a secure base in the party's grass roots.
He is a veteran of the Vietnam War, and spent five years as a prisoner- of-war.
Though he is a conservative, Mr McCain is seen as fiercely independent, and is well-liked beyond the party. He was behind this year's attempt to pass a Bill regulating the tobacco industry and an effort to clean up campaign finance, both of which were shot down, largely by his own side.
Mr McCain will have plenty of strong support from colleagues in Washington, as he is considered to be a political heavyweight and one of the most honest men in politics. "Many, many Republicans and Americans yearn for a new kind of leadership," said Warren Rudman, the committee co-chairman and himself a former senator. "John McCain is unique in his ability to offer conservative, independent, experienced leadership." But his independence antagonises other colleagues, who consider him a loose cannon.
Next week another but very different Republican Senator is also likely to make his move. John Ashcroft of Missouri is a religious conservative with close links to two of the most influential figures in the new Religious Right, Gary Bauer and James Dobson.
The Republican Party has become dominated by hardline southern conservatives, but this year's Congressional elections and the furore over the scandal surrounding President Bill Clinton have left it battered and bleeding. The primaries to select candidates do not start until 2000, but candidates will want to move smartly to establish their ground and secure funding.
One reason why Republicans are moving early is that Steve Forbes, the billionaire magazine publisher who spent $30m on an aborted campaign in 1996, is likely to declare soon and he has boundless funding.
The former vice-president Dan Quayle, former governor of Tennessee Lamar Alexander and former senator Jack Kemp are all waiting in the wings. The Governor of Texas, George W Bush, son of the former president George Bush, has said he will not decide whether to run until the spring.
The race for the candidacy will be hard-fought, with Mr Bush the present front-runner in terms of popular support and name recognition, but plenty of others have more backing among the party's most important supporters.
Money will be the key. A candidate, to be serious, needs about $20m. This will be little problem for Mr Forbes, and Mr Bush also stands a good chance of building fighting funds quickly but others may struggle. It could be that candidates spend so much money and fight so hard in the primaries that, by the time they reach the Presidential election in November 2000, they will have exhausted themselves.Reuse content