The poll, taken in Iowa by PSI of Virginia, shows the presidential election will be largely decided by money. Mr Forbes is funding his own campaign; George W Bush has collected more cash than any other candidate. Other contenders may be forced to drop out by a shortage of cash.
The survey of those likely to vote in Saturday's Iowa straw poll, a key gauge of Republican sentiment, shows that Governor Bush of Texas still holds a solid lead, with 37 per cent of voters likely to back him. Mr Forbes has jumped into second place with nearly 15 per cent, a big increase from the 2 per cent which he scored in earlier Iowa polls. Elizabeth Dole, who had been second, has fallen to third place with 9 per cent.
Though it is more than a year until Americans vote for their next president, the straw poll is likely to winnow out the Republican field. It shows Patrick Buchanan, Alan Keyes, Lamar Alexander and Orrin Hatch all with less than 4 per cent of the vote. "The Forbes surge seems to have come primarily at the expense of Dole and to a lesser extent from the other candidates, save Bush and [Gary] Bauer," said Craig Tufty of PSI.
Mr Buchanan is rumoured to be considering switching to the independent Reform Party to register his anger at the way the Republicans have been commandeered by Mr Bush; Mr Bauer is a Christian fundamentalist with deep pockets who will probably continue. The others may have to drop out. Dan Quayle, former vice-president, has 5 per cent of the vote and is facing financial problems. John McCain, the senator from Arizona, has not contested Iowa and will target other states, particularly South Carolina and New Hampshire.