John McCain is nursing a narrow lead over Barack Obama in Florida even as voters say the Democrat is more trusted to handle their most important issue: the economy, according to a new Miami Herald poll.

The poll, taken Sept. 14-17 -- when Wall Street turmoil dominated world and national news -- gives McCain a 47 to 45 percentage point lead over Obama, with 7 percent undecided. The poll's margin of error was 3.5 percentage points.

But if the economic crisis deepens, ''Obama is in a position to improve his poll numbers, given the confidence in his handling of the economy,'' said Democratic pollster Tom Eldon of Schroth, Eldon & Associates, who conducted the poll with Republican pollster Kellyanne Conway. The poll was also underwritten by the St. Petersburg Times and Bay News 9.

McCain's razor-thin lead virtually guarantees, however, that ''once again, Florida is going to be the pivotal battleground state in this election,'' he said.

The survey of 800 likely voters echoed the economic jitters of the nation, as 43 percent of voters said the economy should be the next president's top concern. That's a three-to-one margin over the next two top issues: managing the war in Iraq, at 14 percent, and protecting us from terrorism, at 12 percent.

When voters were asked who will be the most effective commander in chief, McCain was favored 55 to 38 percent. For those who said terrorism was their top issue, McCain got a whopping 92 percent of the vote. When it came to managing the war in Iraq or Afghanistan, McCain was favored 54-40 percent.

But when asked which of the candidates will best ''improve the economy,'' Obama was chosen over McCain 49 to 40 percent for all voters and 53 to 30 percent among independent voters. For voters who also answered that the economy is the most important issue, Obama led 56 to 34 percent.

Read the full story at MiamiHerald.com.