On the assumption that President Barack Obama survives for a full four-year term — for it is generally assumed that, as the first African-American president, he will face a higher than average risk of assassination — what changes will he bring to the United States and the world? It is remarkably difficult to say, for no president since Lyndon Johnson has come to office with so few commitments to specific policies. Having seen off the Hard Man of the Democratic party, Obama must now defeat the Hard Man of the Republican party in November. (Clinton promised to “obliterate” Iran if it attacks Israel; Senator John McCain has proposed threatening North Korea with “extinction”.) But it will be hard for Obama to lose while the United States is plunging into a deep recession and the Republican candidate is still shackled to the Bush administration’s war in Iraq.