Hillary Clinton’s worst fears were confirmed yesterday when Barack Obama, the Democrat senator who has electrified American politics, officially declared himself a presidential contender for the first time.

Despite only two years in the Senate, Mr Obama’s political rise has been so meteoric that his announcement makes him the biggest Democrat figure to enter the presidential arena. It is a move that poses the greatest threat to the White House hopes of Mrs Clinton, who has yet to declare her candidacy but is widely expected to.

After months of speculation that the talented but inexperienced Mr Obama would enter the race, he said that he was setting up a presidential exploratory committee. The move, which allows him to raise money, is the first step before an expected formal announcement on February 10, a campaign that could make him America’s first black President.

Unlike Mrs Clinton, who voted for the Iraq war, Mr Obama has opposed it from the outset. He has presented himself as an articulate antiwar candidate and liberal alternative to the former First Lady.

Although she has been at pains to position herself as a centrist since she entered the Senate in 2001, many Democrats fear that she is too polarising a figure to win over Middle America. Mr Obama is viewed as the most plausible “Stop Hillary” candidate for Democrats concerned about her electability. His candidacy is likely to appeal to the party’s grassroots voters, who play an influential role in the primary nominating contests.

His colour — his mother was white, his father a black Kenyan — will also attract AfricanAmericans, traditionally part of Mrs Clinton’s political base.

Mr Obama, 45, used a video broadcast on his website to explain his decision. “I certainly didn’t expect to find myself in this position a year ago,” he said. Referring to the adulation he has received from crowds across America in recent months, he added: “Running for the presidency is a decision no one should make on the basis of media hype or personal ambition alone.”

Mr Obama, reprising the main theme of his bestselling memoir, The Audacity of Hope: Thoughts of Reclaiming the American Dream, said: “I’ve been struck by how hungry we all are for a different kind of politics.” Aiming to convince voters that his inexperience and freshness is what is needed to cure the ossified ills of US politics, he said: “Today our leaders in Washington seem incapable of working together.

Politics has become so bitter and partisan, so gummed up by money and influence, that we can’t tackle the big problems that demand solutions.”

Mr Obama’s announcement brings to 25 the number of politicians from both main parties who have either declared presidential candidacies, or expressed an interest in running.

He can now expect operatives from rival campaigns — not least from inside the Clinton camp — to be digging feverishly for dirt.

The obstacles

Inexperience He has been a senator for only two years and has never been tested by a tough campaign

Drugs He admitted that he used cocaine and marijuana in his youth

Judgment He admitted he had been “boneheaded” in buying land from a now indicted political fundraiser

Opponents Hillary Clinton has more money, more guile and the best political strategist in the country — her husband

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