TALLAHASSEE — The proposed gay-marriage ban Florida voters are deciding now could be the electoral chicken to the presidential race’s egg.

Which came to the polling booth first, opponents of Amendment 2 or supporters of Sen. John McCain? Proponents of the marriage amendment or backers of Sen. Barack Obama?

Neither. Or both. Maybe.

“I think that both Barack Obama and Sarah Palin’s appearance on the ballot helps the marriage amendment considerably,” said John Stemberger, state chairman of Yes2Marriage.org, the group that has led the Amendment 2 campaign.

He said the support of evangelical Christians for the amendment is nearly matched by black voters.

“Hundreds of thousands of black American Democrats support this issue. This is a moral issue and a human issue,” said Brenda Lewis-Williams, a Bay County resident, and a member of the Yes2Marriage campaign.

Opponents have put together their own coalition of seniors, clergy and rights advocates who represent large blocs of Florida voters.

A Mason-Dixon poll released Thursday said Amendment 2 had 56 percent of support among likely voters surveyed, short of the 60 percent required. Undecided voters were at 7 percent and may decide the issue.

Younger voters, many of whom are registered for the first time and energized by the Obama campaign, tend to oppose the proposal. But the effect of either presidential campaign on Amendment 2 is hard to pin down in an election that could see greater than 80 percent turnout of registered voters.

“The honest answer is it’s an unknown. Nobody knows how many of the new registrants are going to show up,” said Derek Newton, campaign manager for Florida Red & Blue, the lead group in opposition to the proposal. “We have this kind of wash with higher-than-average participation of young voters and probably higher than average participation of African Americans, who tend to support it.”

In 2004, gay-marriage ban amendments appeared on ballots in 11 states. All passed.

In the two states where overall loser Sen. John Kerry won, Oregon and Michigan, the marriage amendments failed to reach the 60 percent now required for passage in Florida. President George W. Bush won the nine states that exceeded three-fifths voter approval for the amendments.

The appearance of a ballot question that favors one end of the political spectrum is no guarantee of success for candidates who align with one side. In 2004, Floridians approved a minimum-wage amendment by 71.3 percent on a proposal attractive to Democrats. Kerry lost the state with 47.1 percent of the vote.

In addition to Florida, there are marriage amendments on the ballot in Arizona and California, fewer than the 11 states in 2004.

“Unlike 2004 and 2006, there really is no theme that is dominating this year’s crop of ballot measures,” said Jennie Drage Bowser, with the National Conference of State Legislatures.

Droves of new voters may not even take on the six proposed amendments on the Florida ballot.

“We don’t know how many of (new voters) are going to drop off down the ballot. Amendment 2’s all the way at the bottom,” Newton said.

Before Gov. Sarah Palin was named to the Republican ticket, Amendment 2 might have helped moderate McCain more.

“I think the Christian right is the most significant part of the Republican base in Florida,” said Lance DeHaven-Smith, a professor of public administration and policy at Florida State University. “There was some concern that John McCain was not very appealing to the Christian right and they would stay home. Given that Gov. Palin’s on the ballot, the independent effect of the marriage amendment is probably not that great.”

The same is likely true of the effect of the presidential race down-ballot.

“Among the core base supporters, passions are pretty high on both sides,” Newton said.