John McCain's decision to pull out of Michigan last week demonstrated how his campaign is now on the defensive across a shrinking map of battleground states.

With less than a month to go before the November 4 presidential election, Barack Obama either has a solid lead or is well positioned to win states accounting for 264 electoral college votes, only six short of the magic 270 number needed for victory.

Mr McCain has solid leads or is well positioned in states accounting for 181 electoral college votes.

That leaves the fight focusing on just seven “toss-up” states representing 93 electoral votes - Colorado, Nevada, North Carolina, New Hampshire, Virginia, Ohio and Florida.

Mr Obama appears set to capture New Mexico and Iowa - both states won by President Bush four years ago and which, when combined with John Kerry's 251 electoral college total, would put him within touching distance of the White House.

The Democrat's ambitious plans to target 18 Republican states have retreated a little with the likes of Alaska, Idaho, North Dakota and Georgia, as well as probably Montana, beyond his reach.

But he is still making a sustained effort in Indiana, Missouri and North Carolina, in addition to the toss-up states.

Republicans still believe that they can capture states won by the Democrats four years ago, with a target list of New Hampshire, Pennsylvania, Wisconsin and Minnesota.

Of these, New Hampshire - the scene of Mr McCain's primary comeback in January - is the most likely.

One scenario would have Mr Obama winning Iowa, New Mexico and Colorado but losing New Hampshire - resulting in a 269-269 draw in the election.

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