With the Democratic nomination a certainty, Barack Obama now faces the task of uniting his party against the Republican candidate John McCain.

Although his rival Hillary Clinton has not officially conceded defeat, results from last night’s primaries have pushed Obama over the threshold of delegates needed to be nominated. “Because of you tonight I can stand here and say that I will be the democratic nominee for the president of United States of America,” he told a crowd at the headquarters of the US’s leading pro-Israel lobby AIPAC.

Although he will only officially become candidate at his party’s convention in August, campaigning has already started for Obama, who immediately addressed the Iranian question: “I will do everything in my power to prevent Iran from obtaining a nuclear weapon, everything,” he said.

In her state of New York, Senator Hillary Clinton graciously paid tribute to her rival: “It has been an honor to contest these primairies with him, just as it is an honour to call him my friend and tonight I would like all of us to take a moment to recognise him and his supporters for all they have accomplished.”

With the race for the White House effectively on and the two candidates neck and neck in opinion polls, it’s now going to be a battle of personalities and contrasting styles all the way to November’s presidential election.

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