Christopher Cooper reports on the presidential race from Columbia, Mo.

Barack Obama is mixing surprise and his hefty campaign bankroll to project an air of inevitability as the presidential race heads into its final days.

After weeks of sticking to the basic campaign format, the Obama camp is pulling some surprises out of its hat. Today came the news that Obama will stage a Monday rally in Florida before the election, this time in Jacksonville. The state is tight, polling suggests, and Obama win in the Sunshine State would severely damage Republican rival John McCain’s chances of taking the White House.

On Thursday, the campaign added a stop in Springfield, Mo., for Saturday, squeezing it into a schedule that already included Nevada and Colorado. Polling has pinballed in the Show-Me State during the month of October, with surveys alternately showing McCain running at a three percentage point advantage – or an eight-point deficit.

Running consistently strong, however, is Jay Nixon, the Democratic candidate for governor, who leads his Republican rival by as much as 19 points in polls. Nixon appeared with Obama at a rally in Columbia, Mo. Thursday night. Missouri was a pivotal battleground for Democrats in 2006, yielding a Senate seat following an extremely tight and brutal contest. Counting Saturday, Obama will have logged 13 campaign events in Missouri since clinching the nomination in early June.

Though the Obama campaign generally issues an advance written campaign schedule out early to reporters, Saturday’s Missouri stop was a verbal addition. “We’ve always hung loose and tried to put together a schedule that made political sense,’’ said David Axelrod, chief political strategist for the Obama campaign. Our goal is to be as light on our feet as possible.’’

Axelrod said the event was added within the last week or so. This week, Obama aired a national 30-minute television ad and is resuming spending on television ads in Georgia and North Dakota, two states Obama didn’t seem likely to win earlier. But polls show both states have tightened, and early voting statistics in Georgia have the Obama campaign convinced it is competitive there.

The smother-the-competition strategy includes a measure of bluff. On Friday, the campaign said it planned to begin advertising in Arizona, McCain’s home state. Though polls have tightened there, McCain appears comfortably ahead in most recent surveys. Most Obama campaign officials don’t include Arizona in their roster of winnable states.

If McCain is intimidated by Obama’s activity on the airwaves and the hustings, he isn’t letting on. He has stuck doggedly to a campaign schedule that focuses heavily on Ohio and Pennsylvania, two states rich in electoral votes and the linchpin to his prospects for victory. Pennsylvania went to the Democrats in 2004 but only by a small margin.

For Obama, there will be more additions to the rally schedule in the final four days, Axelrod said. One slot still open: Election Day. As late as a week ago, aides had said Obama would likely vote and then spend the day in Chicago before staging his final event of the political season there. Axelrod now says Obama likely will stage some sort of campaign event outside of Illinois on Tuesday.