Multi-millionaire Steve Forbes has withdrawn from the US presidential race after poor showings in primaries in New Hampshire and Delaware.

"I have no regrets and you shouldn't either, for together you and I have transformed the public agenda," he told supporters in Washington.

"With every ounce of energy and passion that I have, I aim to set the stage, with your help, for the next great conservative century."

Mr Forbes' announcement follows his third place behind front-runner George W Bush and Senator John McCain in the Republican primary in Delaware on Tuesday.

He said he had not decided whether to back either of his opponents.

News of his decision filtered out on Wednesday when advisers said he had informed them he had cancelled his Michigan campaign schedule.

Millionaire bid

It is the second consecutive failure for Mr Forbes, who has never been elected to public office.

He has financed his two bids with at least $60m of his estimated $440m personal fortune, which stems from the publishing empire inherited from his flamboyant father, Malcolm Forbes.

With no prior political experience, he entered the 1996 presidential campaign with a radical flat-tax proposal and a series of negative advertisements that wounded eventual Republican nominee Bob Dole.

But he failed to expand his power base or organise in key states, and his candidacy failed.

Mr Forbes began mounting his 2000 bid almost as soon as the 1996 presidential campaign ended, shifting to the right on abortion and other social issues in an attempt to rally staunch conservatives.

Unlike 1996, Mr Forbes built a strong grass-roots organisation this year, spending hundreds of thousands of dollars on some of the country's top political talent.

In the Iowa caucuses last month, Mr Forbes finished a solid second behind Mr Bush, but that proved to be his high-water mark.

Showdown in South Carolina

Mr Forbes' withdrawal clears the way for a two-way race between Texas Governor Bush, and Senator McCain of Arizona, whose poll ratings have climbed since his surprise win in New Hampshire last week.

Both are eager to attract Mr Forbes' supporters. Analysts say Mr Bush stands to benefit from Mr Forbes' withdrawal, because the retiring candidate attracted conservative votes that might otherwise have gone to the Texas governor.

The next big event in the presidential race is South Carolina's primary on 19 February.

Alan Keyes is the only other contender left in the Republican field, but is not considered a serious challenger for the nomination.