An effort to rewrite the Florida Constitution to prohibit gay marriage is falling short of the numbers needed for victory in the Nov. 4 election, a Sun Sentinel and Florida Times-Union poll shows.

The poll of 600 likely voters shows support for Amendment 2 at 53 percent, less than the 60 percent approval rate required to change the constitution.

The gay-marriage question is one of six statewide referendums on this year's lengthy ballot. The poll found uncertainty high on all of the rest, which range from tax breaks for homeowners who install hurricane protection to elimination of racist language from the state constitution.

Backers of the gay-marriage ban say the poll should be a wakeup call to conservatives to vote. Opponents say the poll shows they have made progress in explaining that the proposal could jeopardize domestic partnership benefits that many governments and companies offer straight and gay employees.

Gay marriage has been prohibited under state law for more than a decade, but supporters say a constitutional amendment would protect the law from court challenges.

The amendment would define marriage as between a man and a woman and would say that no "substantial equivalent" is legal either. Opponents fear that if the amendment passes, conservatives will raise legal challenges to domestic partnership benefits, from health insurance to hospital visitation rights.

Voters are split over the use of the term "marriage," said Del Ali, whose firm conducted the poll. The poll found strong sentiment for same-sex couples' having the same legal rights as married heterosexual couples. Seventy-seven percent of those polled favored equal rights for same-sex couples, while 15 percent were opposed and 8 percent were undecided.

Support for Amendment 2 was weakest among women and Democrats and strongest among men and Republicans. Just over half of the independents surveyed opposed the amendment, almost as high as the Democratic opposition.

Sheila Hoffer, 64, a Democrat from Boynton Beach, is among those searching for answers on what the amendment would do. She says she thinks marriage should be reserved for a man and a woman, but says she wants to see same-sex couples have the same legal rights.

"If two people are in a committed relationship, they should have the same rights," Hoffer said.

But for Allison Porter, 21, an independent voter in Deerfield Beach, the definition of marriage is paramount.

"Because I'm Christian, I believe in what the Bible has set up as marriage, and that's one man and one woman," she said.

Amendment 1 is the only one that would remove a provision from the Florida Constitution. It would repeal a clause ithat allows legislators to ban Asian immigrants from owning land.

Florida is the last state in the nation with a so-called "alien land law," a standard drawn in 1926 to target Japanese immigrants. Legislators never invoked this authority, however, and it couldn't be enforced today because of equal-protection laws.

Supporters describe Amendment 1 as a symbolic vote to remove racism and discrimination from the constitution.

In the poll, 44 percent favored removing the discriminatory language, while 37 percent were opposed and 19 percent were not sure.

Winnie Tang, president of the South Florida chapter of the Organization of Chinese Americans, said she hoped voter education over the next two weeks would boost support for the change.

"People are shocked to learn there is still this kind of racist, discriminatory language in the state constitution," she said.

Scott Wyman can be reached at swyman@sunsentinel.com or 954-356-4511.