SAN DIEGO -- Gay rights advocates in San Diego Wednesday praised a federal judge's decision to strike down Proposition 8, the state's voter-approved ban on same-sex marriage.

"I am overjoyed that the U.S. District Court overturned Proposition 8," San Diego City Councilman Todd Gloria said. "I know our fight to secure this right is not over, but I am confident this civil right will be confirmed and marriage equality will be realized."

The ruling is expected to be appealed to the 9th U.S. District Court of Appeals and eventually the U.S. Supreme Court.

San Francisco-based U.S. District Judge Vaughn Walker presided over the non-jury trial of a lawsuit alleging the voter-approved 2008 measure violates the equal protection rights of gay and lesbian couples by preventing them from marrying.

In a 136-page ruling, Walker wrote that the proposition "both unconstitutionally burdens the exercise of the fundamental right to marry and creates an irrational classification on the basis of sexual orientation."

"Proposition 8 fails to advance any rational basis in singling out gay men and lesbians for denial of a marriage license," Walker wrote. "Indeed the evidence shows Proposition 8 does nothing more than enshrine in the California constitution the notion that opposite-sex couples are superior to same-sex couples."

Walker issued an order barring the enforcement of the law, but proponents of Proposition 8 were expected to appeal -- likely all the way to the U.S. Supreme Court. Walker issued a stay on the ruling until at least Friday, meaning same-sex marriages will not immediately resume in the state. Supporters of Prop 8 had asked for a stay, saying allowing couples to marry pending the appeal would create confusion if Walker's ruling is eventually overturned.

"We as a community really need to celebrate," Gloria said, adding that he expects thousands to attend the 6 p.m. march.

Officials with the San Diego LGBT Community Center also hailed Wednesday's ruling.

"This is a great day for every American who believes that the U.S. Constitution guarantees us all equal treatment and due process," said Delores Jacobs, chief executive officer of the San Diego LGBT Community Center.

"The decision reminds us all that in America there are laws, principles and freedoms that are fundamental; the people cannot simply decide to discriminate against a group they may not like," she said.

But Randy Thomasson, president of SaveCalifornia.com -- Campaign for Children and Families, decried Walker's ruling as "a terrible blow" to marriage and voter rights.

"Judge Walker has ignored the written words of the Constitution, which he swore to support and defend and be impartially faithful to, and has instead imposed his own homosexual agenda upon the voters, the parents and the children of California," Thomasson said.

"This is a blatantly unconstitutional ruling because marriage isn't in the U.S. Constitution," he said. "The Constitution guarantees that state policies be by the people, not by the judges, and also supports states' rights, thus making marriage a state jurisdiction."

Thomasson added that as "a Californian and an American, I am angry that this biased homosexual judge, in step with other judicial activists, has trampled the written Constitution, grossly misused his authority and imposed his own agenda, which the Constitution does not allow and which both the people of California and California state authorities should by no means respect."

Sen. Christine Kehoe, D-San Diego, the region's first openly gay elected official, applauded Walker's decision "on behalf of equality today for all loving and committed couples in California."

"These men and women deserve the right to marry, and this decision reinforces that our society is a fair and just place," Kehoe said. "I hope the community celebrates today's victory and remains vigilant in the pursuit of civil rights for all Californians."

In March 2000, California voters approved Proposition 22, which specified in state law that only marriages between a man and a woman are valid in California. But in May 2008, the state Supreme Court ruled the law was unconstitutional because it discriminated against gays, and an estimated 18,000 same-sex couples got married in the ensuing months.

Opponents of same-sex marriage quickly got Proposition 8 on the November 2008 ballot to amend the state constitution, and it was approved by a margin of 52.5 percent to 47.5 percent.

The approval of the measure led to statewide protests and lawsuits challenging the legality of Proposition 8.

In May 2009, the California Supreme Court upheld Prop. 8, but also ruled that the unions of roughly 18,000 same-sex couples who were wed in 2008 would remain valid.

Various gay and lesbian rights groups have considered putting the issue back on the ballot, but even the supporters of same-sex marriage have sparred over when to ask voters to reconsider the issue.

The Constitution's 14th Amendment guarantees equal protection under the law and the right to due process -- two key issues activists cited in their opposition to the ban on same-sex marriages.