Whether that fragile coalition will last from the argument until a decision is handed down within the next couple of months is anybody's guess.
A key swing vote, Justice Sandra Day O'Connor, in many cases appears to argue one side from the bench but joins the other side in a decision.
However, it was clear from the argument in the Supreme Court Wednesday that O'Connor and moderate Justice Anthony Kennedy will decide the case no matter how they vote, with the remaining three conservatives and four liberals taking opposite sides.
If O'Connor and Kennedy join the conservatives, then vouchers would be approved by a 5-4 vote.
Though the argument Wednesday involved a pilot voucher program in Cleveland, any decision will apply nationwide, and will be crucial to President Bush's sweeping proposal to make school vouchers available across the country.
During Wednesday's argument, O'Connor and Kennedy appeared to accept the argument of lawyers defending vouchers -- including U.S. Solicitor General Theodore Olson -- that the Cleveland program is "neutral" because it offers choices beyond religious schools and because the funding is given to parents, not directly to the schools.
"The courts have made a distinction between (public) money going directly to (religious) schools," Olson said, " ... and individuals making choices" to spend that money for religious schools.
In turn, the two key justices appeared to reject the argument of lawyers for voucher challengers, who contended that since the overwhelming majority of schools participating in the program are religious, and since 99.4 percent of the students benefiting from the program are in religious schools, then the program is an unconstitutional public subsidy of religion.
The pilot program being reviewed by the Supreme Court grew out of a crisis in the Cleveland schools, which were considered substandard in the mid-1990s.
In 1995, a federal judge overseeing a Cleveland desegregation case ordered the state superintendent to take over control of the local school district.
Ohio's General Assembly then adopted the pilot voucher project, applying it to any school district taken under the jurisdiction of a federal court. Cleveland's was the only school district under such jurisdiction in Ohio.
The program gives private school scholarships to Cleveland school district children from kindergarten through the eighth grade and requires participating private schools to cap their annual tuition at $2,500.
For low-income families, the program provides 90 percent of the costs of going to a private school. If money is left over after low-income families apply, the program pays 75 percent of the costs for other families.
For the 1999-2000 school year, 3,761 students enrolled in the program; 60 percent were from families at or below the poverty level.
Though the program was designed to give scholarships to non-sectarian and sectarian schools, 96 percent of those enrolled in 1999-2000 used the money to attend religious schools (more than 99 percent now).
Of the 56 schools registered to participate in the program for that school year, 46, or 82 percent, were religious. A federal appeals court noted that "the handbooks and mission statements of these schools reflect that most believe in interweaving religious beliefs with secular subjects ... (include) instruction in religion ... interweaving Christian doctrines with science and language art classes. ... "
Originally, the program was also designed to give tuition to Cleveland students so they could attend a suburban public school, but none of the surrounding school districts chose to participate.
Students are also given the option of going to a "community school," sometimes called "charter schools." But those schools are still in the public system, and the state would give money directly to such a school if a family chose to send a child there.
Community schools make up only a small percentage of the facilities participating in the program.
In one of the cases accepted by the Supreme Court, the parents of public school children and a church pastor filed suit in July 1999 against the Cleveland program, saying it violated the separation of church and state.
Eventually, a federal judge issued a preliminary injunction against the project, saying it violated the First Amendment's ban on the establishment of religion.
Last December, a divided appeals court panel ruled 2-1 that the program violates the Constitution because it "has the primary effect of advancing religion" and "constitutes an endorsement of religion and sectarian education."
The school district and Ohio officials then asked the Supreme Court for review, and the pilot program has been allowed to continue while the high court decides the case. That case, combined with two others on the same issue, was heard by the justices Wednesday.
Assistant Ohio Attorney General Judith French, speaking for the school district, told the justices, "It (the voucher system) offers a neutral program that gives true choice to parents," and is "open to all comers," regardless of religious beliefs.
Since the benefit being given by the state to parents is money in the form of vouchers, "it's inherently neutral," French said.
Justice David Souter, one of the court's four liberals, disagreed from the bench.
"At the end of the day the effect is ... a massive amount of money going to religious schools here," Souter said.
Chief Justice William Rehnquist then spoke up in French's defense, saying, "Where the parents do the choosing" -- instead of a direct subsidy from government -- "it's a different ball game."
Columbus, Ohio, attorney David Young spoke for parents whose children are participating in the program.
"Not one (public) dollar flows to a religiously funded school," Young said, "but for the choice of a parent."
Speaking for the Bush administration in support of vouchers, Olson said the justices would have to weigh the plight of Cleveland schools in their decision.
"Is the government endorsing religion? That has to be answered in light of what was going on" in the district's substandard schools," Olson said.
He insisted the voucher program was about "a purely private choice."
Washington attorney Robert Chanin represented the challengers in a sometimes heated extended argument before the justices.
In the ongoing Cleveland program, "millions of dollars ... are transferred from the public treasury to sectarian private schools," Chanin said.
Chanin cited the "establishment clause" of the First Amendment -- "Congress shall make no law respecting the an establishment of religion, or prohibiting the free exercise thereof."
"If those funds are attributable to the state, then that program violates the establishment clause," he insisted.
In the face of repeated challenges from the bench from Kennedy, O'Connor and conservative Justice Antonin Scalia, Chanin maintained that the program was not really a choice.
In response to continued poking by Scalia, who contended that Cleveland schools had to do something to solve their problems, Chanin said with passion, "I do not believe that a crisis in the Cleveland public schools is a mandate to abolish the establishment clause."
Former law professor and retired U.S. Judge Marvin Frankel of New York also argued briefly for the challengers.
Speaking from a wheelchair in a subdued voice, Frankel told a hushed courtroom that the voucher program could not even survive a challenge under the Ohio Constitution, and should not survive a challenge under the U.S. Constitution.
Much of activity surrounding Wednesday's argument had a carnival-like atmosphere.
Supreme Court police said spectators began lining up at 8 p.m. Tuesday for the 10 a.m. Wednesday argument.
Pro-voucher demonstrators were bused in from surrounding areas, police said, and about 350 of them formed a boisterous protest in front of the Supreme Court plaza while the case was argued inside the building.
When counter-demonstrators entered the fray, police had to break up several scuffles and one woman was pushed to the ground, injuring her mouth.
The courtroom was partially filled with guests of the justices, including Sen. Ted Kennedy, D-Mass. Retired actress and neo-Republican activist Bo Derek attended as well.
(No. 00-1751, Supt. Zelman et al vs. Simmons-Harris et al; No. 00-1777, Hanna Perkins School et al vs. Simmons-Harris et al; and N0. 00-1779, Taylor et al vs. Simmons-Harris et al.)