two-party cast, Bill Clinton and President Bush remembered that they really admired his act.

They couldn't wait to call him up and say so.

After all, there's suddenly a swing vote without a candidate, and Perot supporters could be decisive in the two-way race. So the custody struggle is on, a major element of the campaign for the weeks ahead.

Clinton and his Democrats say that as a champion of change, Perot mobilised voters who now should join their cause. Bush countered that his supporters "should feel at home with us''.

Democrat Clinton is the immediate beneficiary, since the first public opinion polls minus Perot reflected the attention he's commanded at the Democratic National Convention. A week in the spotlight, even with rationed television coverage, boosts any candidate, at least temporarily.

Longer term, Perot's absence probably will help Bush in the November 3 election, which really is 50 separate contests for the electoral votes of each state, because Perot was likely to appeal to a relatively conservative constituency, especially in the suburbs, the South, the Sun Belt, and the West, all vital to Republicans.

Then again, the complexities of a three-way contest, in which winning wouldn't require majorities, probably would have been a plus for Clinton as a challenger. And the Bush campaign could have been pushed to defend almost every state, against rivals who could pick and choose electoral vote targets.

Now both tickets can do it.

But there are few certainties in a political campaign, and almost none in the tumult of a national convention.

Perot upstaged the off-Broadway Democrats on Thursday with his concession that he couldn't win the November 3 election as an independent, couldn't goad Congress out of gridlock even if he did, and therefore wouldn't run.

That rewrote the script just as Clinton launched his final drive for the White House at the finale of the Democratic convention. It also gave the new Democratic nominee a prime-time opportunity to appeal to Perot's backers.

Bush had planned to lay low for the duration of the Democratic convention, but the Perot withdrawal lured him out of the Wyoming wilds.

The president telephoned Perot, invited his supporters to the GOP side, then held a news conference with White House reporters flown in to Pinedale, Wyoming, too remote to make television competition for Clinton.

While Perot said he wasn't endorsing either candidate, he said Democratic revitalisation, presumably because of the centrist Clinton ticket, had led him to conclude he couldn't win the election.

Clinton liked the sound of that, and thanked Perot personally. But the dropout dented the strategy of his all-Southern ticket.

In a three-way race, Bush would have faced a major problem with Perot prying away GOP votes in a region that has become part of the Republican electoral base.

Now it is a head-on campaign, Bush versus Clinton, with no diversions.

The Democrats will have to intensify their effort to win in the Northeast and the industrial Midwest, traditional liberal bastions.

And Clinton's new-look ticket has work to do among sceptical liberal Democrats.

The night before Perot quit, Sen. Bob Kerrey of Nebraska told the convention the Texas independent was gaining supporters "because he isn't one of us, he isn't a politician''.

"In the end ... he will cave in and go away,'' Kerrey said prophetically.

"But the restless souls behind his candidacy won't go away.''