WASHINGTON -- This year's Republican presidential contest is suddenly hotter than anyone predicted, a seesaw struggle for momentum between George W. Bush and John McCain.
The focus of the campaign is shifting, though, along with the terrain. Over the next three weeks, both men will run coast to coast, competing in primaries and caucuses in two dozen states.
And as they do, a new phase of the race will take off: the hunt for enough delegates to win the nomination.
Each campaign was scrambling yesterday, after McCain's surprising comeback victory in Michigan, to revise its plan for the next round of primaries. And each claimed that the calendar would work in its favor.
"The truth of the matter is, we didn't need a delegate strategy until yesterday," said Dan Schnur, a McCain campaign spokesman.
Roughly half the delegates chosen in the next three weeks will be awarded in primaries where only Republicans can vote. That should benefit Bush, who has been defeating McCain by margins of better than 2-to-1 among voters who identify themselves as Republicans.
The rest of the delegates will come from states where either independents or independents and Democrats can also vote. Under similar rules in New Hampshire and Michigan, McCain came out ahead.
McCain still faces an uphill fight against his better financed and better organized rival. But the Arizona senator has defied the odds, and has gained the early lead in the delegate count, by picking the right states in which to challenge Bush.
Next Tuesday, three states will hold delegate contests -- Virginia, Washington and North Dakota. McCain is focusing on Virginia and Washington to avoid a possible shutout.
But the days of gaining an advantage with one well-placed victory are about to end, as the need to win delegates intensifies.
Aiming for Super Tuesday
With time tight and money an important factor, both campaigns will have to target their efforts carefully for Super Tuesday, when 13 states, including Maryland, will hold Republican delegate tests.
McCain figures to do well in New England, where five states hold primaries, and Bush should prevail in Georgia, the only Southern state to vote that day. New York, Ohio and Maryland could wind up splitting their delegates between the two men.
But the Republican who grabs the biggest prize of all, California's 162 delegates, is likely to emerge with the lead in the delegate count.
Up to now, Bush has been ahead in the California polls. The McCain camp says it can turn that around over the next 12 days. Bush campaigned in California yesterday, and both men are likely to spend more time there than elsewhere between now and March 7.
"If we can come out of that day winning the delegates in California and showing strength in New England and New York, we're either going to be the winner or it's going to be a fight that goes to June," when the primary season ends, said John Weaver, McCain's political director.
Poll results in doubt
A new poll of New York Republicans by CBS News shows Bush leading by 7 percentage points. But that survey of likely Republican primary voters was completed before McCain's double victories in Michigan and Arizona.
As the candidates head into the biggest primary day in American history, the Bush campaign says it sees the rules of the game finally swinging in favor of the Texas governor.
"I feel like I am going into my strength now," Bush told a television interviewer.
He noted that, after Tuesday, there will be no more days when Republicans hold primaries and there is no Democratic contest on the same day. That could limit crossover support for McCain, the key to his Michigan triumph.
Bush is continuing to attack McCain, with TV ads in coming primary states accusing him of "low road" tactics in Michigan, where voters received phone calls linking Bush to anti-Catholic bias.
But Bush is also trying to show that he, too, can expand the party. The governor courted Latino voters in California, as a way of reminding Republicans that he has been successful in drawing Hispanic votes in Texas.
`I've got to win'
"I've got to win some primaries," the governor told ABC News. "I've got to win next Tuesday in Washington and Virginia and North Dakota."
Under GOP rules, the ultimate objective is to win 1,034 delegates, the majority needed for nomination. But delegate-selection systems vary considerably from state to state.
Not since the 1980s have the Republicans been treated to a competitive nomination race that went beyond the first few primary states. Party politicians are still trying to sift through the complex rules to see which candidate they might favor.
"The truth is, it's different every time," says Bill Harris, a former national party official who is regarded as a rules expert. "And after you factor in the personalities of the candidates, nobody can really predict which way it'll come out."