One is a white, scarred, 71-year-old, short-fused Vietnam War veteran who believes in victory in Iraq, free trade, low taxes, small government and a Supreme Court that will outlaw abortion. The other is a black, 46-year-old, even-tempered cover boy who has never served in the military, wants to end the war, raise taxes on the rich, believes in big government, is open to talks with enemies of the US and supports abortion rights.

No presidential race in modern times provides such a contrast in age, race, personality and governing philosophies than the five-month general election contest between John McCain and Barack Obama now before the US.

The Republican has challenged his rival to ten unmoderated town hall debates across the US to argue the issues, something the Democrat has said he finds appealing.

Mr Obama starts a 17-day economy tour today, days after unemployment hit a 20-year high, the stock market plunged and petrol prices soared to record highs. He begins with events in North Carolina and Missouri, signalling his intention to put into play states won by President Bush, and he will also visit battlegrounds that he lost to Hillary Clinton in the primary contest, such as Pennsylvania.

Both men will compete fiercely for one key group – independent swing voters who could decide what promises to be a highly competitive election – but, with a few exceptions, the men and their policies could not be more different.

If he wins in November Mr McCain will be the oldest president elected to a first term. Mr Obama, by contrast, would be the fourth-youngest. The Republican will run on a national security message and is already painting his opponent as dangerously inexperienced. The Democrat will focus on anxiety over the economy and the Republican brand – repeating at every opportunity that his opponent is running for “George Bush’s third term”.

Although fellow senators, personal relations between them are chilly and Mr McCain is struggling to conceal his contempt for his young rival. As Mr Obama declared victory against Mrs Clinton on Tuesday, Mr McCain ridiculed him in a speech in Louisiana for having said that he would meet rogue leaders without preconditions, a stance Mr Obama has modified.

“Americans ought to be concerned about the judgment of a presidential candidate who says he’s ready to talk, in person and without conditions, with tyrants from Havana to Pyongyang, but hasn’t travelled to Iraq to meet with General [David] Petraeus,” Mr McCain said, highlighting their main foreign policy differences.

Mr Obama is already pivoting to the right on foreign policy, delivering a hardline speech on Iran last week and outlining a staunchly pro-Israeli stance and a Middle East outlook almost identical to that of Mr Bush. Yet his promise to withdraw troops from Iraq by 2010 might not appeal to a general election audience.

The candidates agree on closing Guantanamo Bay, a “cap and trade” system to limit carbon emissions and a more multilateral approach to diplomacy. Yet on nearly everything else they differ greatly.

Mr Obama wants to provide health insurance for nearly all Americans by raising taxes on the wealthy and some corporations. He wants to spend billions more on education and to increase unemployment benefits, and wants a left-of-centre Supreme Court. Mr McCain wants a conservative Supreme Court and believes in a deregulated, supply-side free market solution to most issues, from pensions to education.

OBAMA AND McCAIN: HOW THEIR POLICY POSITIONS DIFFER

Iraq

Obama: Immediate withdrawal; all combat forces out by 2010.

McCain: Keep a large combat force. Hopes to have achieved victory by 2012.

Taxes

Obama: Wants to lower taxes on lower and middle-class families, raise taxes on the wealthy. Wants to raise capital gains tax and close some corporate tax breaks.

McCain: Wants to extend President Bush’s tax cuts, and make further tax cuts for companies and upper-income families.

Healthcare

Obama: Wants ultimately to give health insurance to all Americans. His campaign says it will cost $110 billion.

McCain: Wants to give more choice for people to buy health insurance, but his plan will not provide cover for many uninsured. His aides estimate it will cost up to $10 billion.

Supreme Court

Three vacancies could open up in the next few years among three of the court’s liberal justices.

Obama: Will seek to appoint justices that will protect abortion rights, gay rights, left, tighten gun ownership and maintain ideological balance of court.

McCain: Pledged to shift it decisively to the right, a move that could mean the right to abortion declared unconstitutional.

Trade

Obama: Has campaigned as a protectionist and called for pause on all new free trade deals.

McCain: Unapologetic free-trader.

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