Mr McCain registered with the Federal Election Commission on Wednesday to form a presidential exploratory committee, said former New Hampshire senator Warren Rudman, who will chair the committee.

Sen John McCain's independence may cost him

This was "the first significant step forward in a campaign for president by John McCain," Mr Rudman said.

Mr McCain is the first of what is expected to be a crowded field of Republicans seeking the party's nomination for president.

Texas Governor George W Bush leads the field which includes former Tennessee governor Lamar Alexander, magazine tycoon Malcolm S. "Steve" Forbes, Sen. John Ashcroft of Missouri, and former vice-president Dan Quayle.

One Democrat, former senator Bill Bradley was first to announce the formation of an exploratory committee.

Long Shot

Although the election is almost two years away, polls and predictions have already begun forecasting frontrunners for the race.

George W Bush is the frontrunner for 2000

George W Bush is ahead of not only his Republican counterparts but is even outdistancing his likely Democratic opponent, Vice-President Al Gore.

Mr McCain will have to distinguish himself from the crowded field of hopefuls, and he was in the single digits in presidential preference polls taken earlier this year.

In late spring, more than half of respondents to a CNN/Gallup/USA Today poll had never heard of or had no opinion of him.

High-priced campaigns

As the cost of a presidential bid has skyrocketed, the campaign cycle has lengthened. Candidates must begin raising money early to sustain their campaigns and win federal matching funds.

Political experts estimate that presidential candidates will have to raise $20m to be competitive.

Key states in the nomination process such as California have moved their primary elections forward, forcing candidates to raise more money faster and earlier.

Ironically, Mr McCain joined Wisconsin Democrat Russell Feingold, in writing a campaign finance bill.

The bill would have banned unlimited and unregulated "soft money" donations to political parties, expanded disclosure requirements and regulated so-called issue ads.

Issue ads support the position a candidate takes but supposedly stop short of endorsing the candidate. The bill died in September.

It is not the only issue on which Mr McCain broke ranks with his party. He also proposed national legislation to regulate tobacco.