ST. LOUIS — Get ready for a wild October.

In the 2008 presidential campaign, Democrat Barack Obama's argument for change has been strengthened in the aftermath of problems in the nation's mortgage and credit infrastructure.

But fundamental questions about leadership, and the threats to the nation's economic and national security, have kept the more experienced John McCain competitive in an election that for all practical purposes should have been long ago lost to the Republicans.

If the final month is anything like September was — indeed, like the entire campaign has been — Americans should count on an October surprise.

Here's what to watch:

BATTLEGROUNDS OLD AND NEW

The fight for the 270 electoral votes necessary to win the presidency is narrowing to a familiar finish but with some new twists. McCain just pulled out of Michigan, where economic concerns have predated the latest financial crisis, in order to fight more vigorously in the perennial battlegrounds of Ohio and Pennsylvania.

But some new states are in play in '08. Virginia and North Carolina, growing Southern states on leftward shifts, are within Obama's reach. Colorado, New Mexico and Nevada in the West are recognized as battlegrounds by both campaigns.

SHARPER MESSAGES

Campaign ads will dominate the airwaves and the Internet for the final month. But your last chance to watch the candidates face off will be two presidential debates, one in Nashville on Tuesday and the other at New York's Hofstra University on Oct. 15.

Look for Obama to continue to pound the change argument, that McCain and running mate Sarah Palin would be more of the same kind of Republican White House as George W. Bush.

"The fundamentals are clear to people," Obama's chief strategist, David Axlerod, said. "McCain and Palin support essentially the same direction for this country, a direction that has punished the middle class."

Look for McCain to try to return the focus to energy policy, where he favors more domestic drilling for oil and development of nuclear power than Obama.

"If we do not move this country toward energy independence, it will be impossible for our economy to grow over the long term, and those key issues and those differences are going to be debated very robustly over the course of the two remaining presidential debates, and over the course of the rest of the campaign," said McCain's senior adviser, Steve Schmidt.

But economic woes — Friday's announcement that the economy shed another 159,000 jobs last month was another example — could sidetrack McCain's attempts to refocus on energy.

MCCAIN'S CHALLENGE

The Arizona senator is essentially fighting on four fronts. 1. To distinguish himself from his Republican Party and the policies of George W. Bush. 2. To make Obama look too risky for the challenges of the day. 3. To coax enough independents to give the GOP another chance. 4. To show that, at 72, he is up to the challenges ahead.

McCain's challenge over the next 30 days came through in a focus group of 12 Missouri voters conducted Thursday by pollster Peter Hart for the Annenberg Public Policy Center at the University of Pennsylvania.

Five of the participants were for Obama, three for McCain. The four undecided participants all had voted for Bush in both 2000 and 2004 and were looking for reasons to vote for McCain this time.

Their advice to McCain: Don't just say you're a maverick, but show it on the campaign trail and in the debates.

"I would like him to quit with the talking points, speak from his heart, let us know who he is," said Jean Geitz, 60, an office manager in a pest control company.

"McCain needs to be a little more exciting, a little more dynamic," said Chris Spitzer, 44, a customer service representative.

Most experts believe voter turnout will be large, with more young people and blacks voting than in past elections, a result that could help Obama immensely. Both campaigns are engaging in massive early voting and registration operations.

But the election still boils down to a dwindling number of undecided voters, and their allegiance can still be won.

Contact Chuck Raasch at craasch@gns.gannett.com