John McCain has been goading Barack Obama into visiting Iraq this summer and trying to paint him as a foreign policy naïf who would be hopelessly out of his depth as US commander in chief.

Needled, Mr Obama says he will go abroad before the November election. The itinerary for the trip, likely to take place ahead of August's Democratic Convention, will almost certainly include Iraq and a whistlestop tour of Western Europe, where his popularity is at its height.

The Illinois senator's advisers want to demonstrate to wavering voters at home that an Obama presidency would work wonders for the country's tattered international image.

America's infatuation with Mr Obama has cooled after the dogged primary battles with Hillary Clinton. But his popularity is still head and shoulders above that of President Bush.

With the President due in Britain today, his arrival is expected to cause havoc for passengers. Mr Bush insisted on bringing his multi-plane entourage to Heathrow to ensure rapid access to Downing Street, instead of using a military airfield.

As part of his "victory tour" Mr Bush was in France on Saturday where he and Nicolas Sarkozy made bellicose warnings to Iran and Syria. Tehran was told to stop enriching uranium and Damascus was told off for ignoring warnings on support for terrorism.

Mr Bush said nuclear weapons in Iranian hands would threaten world peace, and Mr Sarkozy added that it would be "totally unacceptable".

Meanwhile, Mr McCain wants to portray his rival as a defeatist with regard to the war in Iraq. This week he offered to "educate" Mr Obama. He added that his opponent cannot talk credibly about a US troop withdrawal since he has not been to Iraq since the 2007 troop build-up known as the surge.

"There are two-year-old Iraqi children who weren't born the last time Obama was in their country," a Republican spokesman said, and this "raises questions about what he is making his decisions on".

However Mr McCain has himself been attacked for bragging on his last Iraq tour that his visit to a market proved that you could indeed "walk freely" in Baghdad. He was accompanied on his walk by 100 US soldiers, while three Blackhawk helicopters and two Apache gunships flew overhead as he toured in a bulletproof vest.

An Obama international tour is likely to tap into the wave of enthusiasm in Europe – particularly Spain, France and Germany, where his colour, youth and, above all, message that jaw-jaw is always better than to war-war have created impassioned interest.