Obama came close to winning four years ago and Democratic U.S. Sen. Bill Nelson trounced Katherine Harris in Duval in 2006. In the Republican tidal wave of 2010, Democrat Alex Sink lost Duval to Rick Scott by less than 6 percentage points. In 2008, John Crescimbeni became the first Democrat to win a competitive election for countywide office since 1995 when he won a special election for an at-large City Council seat and he overwhelmingly won re-election last year.

Jacksonville Republican consultant Susie Wiles, who ran Scott’s gubernatorial campaign, points to transplants moving to the beaches, south and east Duval as part of the reason politics is changing in the county.

“Northeast Florida used to be solidly conservative. It’s not so much any more,’’ Wiles said. “Duval is still conservative, but probably broader minded than it was a decade ago.”

The growing African-American and Hispanic populations also play a key role.

“In the year 2025 the line between whites and nonwhites is going to cross one another, and some years prior to that it’s going to tilt against Republicans,” said former state GOP chairman Tom Slade of Jacksonville. “As Republicans, we’ve got to go sell our philosophy as the right kind of philosophy to people who consider themselves minorities today. That’s the only chance we’ve got.”

In terms of November, though, Slade and other Republicans see a GOP electorate far more energized in Duval than four years ago.

“This is not Obama vs. Romney; This is Obama vs. Obama,” he said. “I think we’re going to have a very good turnout with Republicans, but it doesn’t have anything to do with Romney. From our side, it has to do with whipping Obama.”

Tampa Bay Times researcher Natalie Watson contributed to this report.