Senator John McCain has announced he is "no longer an active candidate" for the Republican nomination in this year's presidential election but offered only conditional support to his rival, Governor George W. Bush of Texas.
Mr Bill Bradley, a former senator, announced he was withdrawing from the Democratic contest and offered his "support" to Vice-President Al Gore in his campaign to win the Presidency. But he said he was not releasing his 412 delegates at this stage.
Mr McCain said he was "suspending" his campaign following Super Tuesday, when he was defeated by Mr Bush in eight of the 12 states where Republican primaries were held, including the crucial states of California, New York and Ohio.
Speaking to the media near his country retreat at Sedona, Arizona, Mr McCain said that Mr Bush had his best wishes in his campaign to become president. But he did not formally endorse Mr Bush and hinted that his future support would depend on whether his rival adopted some of his policies including reform of campaign finance.
Standing beside his wife, Cindy, against a stunning mountain backdrop, Mr McCain said that he would now reflect on how best to continue to serve the country and help bring about the changes that were the purpose of his campaign.
He appeared to dismiss speculation that he might run as an independent or a Reform Party candidate. "I love my party, it is my home. Ours is the party of Lincoln, Roosevelt and Reagan. That is good company for any American to keep," Mr McCain said.
He would take his "crusade" back to the US Senate. "I will keep fighting to give the government back to the people; to keep our promises to young and old alike by paying our debts, saving Social Security and Medicare, and reforming a tax code that benefits the powerful few at the expense of the many."
By "suspending" but not ending his campaign, Mr McCain will keep control of the 231 delegates he won in the primaries so far. He is hoping to use them as leverage with Mr Bush for his reform policies.
Mr Bush, who was campaigning in Colorado although he no longer has any opposition, reacted cautiously to Mr McCain's announcement. The governor badly needs the support of the independents and even Democrats who came out for Mr McCain in large numbers across the country, but there are important policy differences between the two men on campaign finance reform and tax cuts.
There is speculation that Mr Bush would be well advised to choose Mr McCain as his running mate in the presidential election in the autumn as a way of widening his support against Mr Gore, who will also be seeking the votes of independents. So far, however, Mr McCain has refused to consider the No 2 position on the Republican ticket.
Similarly, Mr Bradley yesterday said he had no interest in becoming Mr Gore's running mate.