More than four decades after the landmark Roe v. Wade decision, the Supreme Court is poised to once again wade into a major debate over abortion, an election-year fight complicated by a sudden vacancy on the nine-member bench.

A group of Texas clinics that provide abortions are asking the justices to keep their facilities open, in the face of state restrictions currently on hold. The high court on Wednesday will hear arguments and then decide in coming weeks whether the provisions effectively abridge the constitutional right to first-trimester abortions guaranteed in the Roe ruling.

The stakes are high.

If the Texas laws ultimately are upheld, all clinics performing the procedure in the state would be required to have certification as "ambulatory surgical centers," regulated under the same standards as hospitals. Another challenged provision would force doctors performing abortions to first obtain admitting privileges at a nearby hospital.

The sudden death of Justice Antonin Scalia could complicate the outcome, though. He was perhaps the most outspoken of the current justices to the legalization of abortion.

Last June, he along with three other conservative members opposed a high court order delaying enforcement of the Texas law, while the case was being appealed. The four reliable liberal justices, along with possible swing vote Justice Anthony Kennedy, gave a temporary victory to the clinics in that order, allowing them to remain fully operational.

It suggests there may now be five votes to ultimately strike down the Texas restrictions.

"It's likely to be a 4-4 or 5-3 vote -- a close decision -- and that really highlights how important this vacancy on the Supreme Court is," Carrie Severino, chief counsel of the conservative Judicial Crisis Network, told Fox News. "We see the kind of extreme liberal justices the president would like to put on the bench, who would probably like to remove from states any ability to enact common sense regulations on abortion."

Lawmakers in the state's Republican-majority Legislature have said the regulations contained in the 2013 law -- known as H.B. 1 -- would improve patient care and safety.

Abortion rights groups counter that the law is designed to make it nearly impossible to operate an abortion clinic in Texas. Only 10 such health centers would qualify to stay open, and large areas west and south of San Antonio would have no full-time abortion providers. The Center for Reproductive Rights had sued Texas, on behalf of a coalition of abortion clinics.

After conflicting rulings in the lower courts, the justices are now being asked to weigh in.

A 4-4 tie at the Supreme Court would mean a default victory for Texas, and likely for similar laws in other nearby states, including Louisiana and Mississippi.

But no legal precedent would be established, leaving continued uncertainty nationwide. The high court could later reargue the case, when another justice to replace Scalia is confirmed by the Senate and sworn in for a lifetime appointment.

But abortion rights supporters and progressive groups think victory may still be in reach this round.

"The Supreme Court is going to recognize these decisions for the sham laws that they are," said Elizabeth Wydra, president of the Constitutional Accountability Center. The law's backers "are really just focused on shutting down a woman's constitutional right to choose for herself and really not at all about the health of the woman."

A Fox News poll from August reveals an even split on the abortion issue, which has inevitably become enmeshed in presidential election-year politics.

Forty-seven percent of registered voters surveyed favor abortion rights or consider themselves "pro-choice," while 46 percent oppose the procedure or are "pro-life."

Research from the Guttmacher Institute finds the number of abortions at its lowest level since Roe, remaining steady at about 1.06 million reported procedures in 2011, down about 25 percent since the all-time high in 1990. Since the 1973 Roe decision, about 53 million legal induced abortions were performed through 2011.

After Roe, the high court affirmed the right to abortion in subsequent cases -- striking down provisions requiring a husband's consent for a first-trimester abortion; requiring parental consent for an unmarried woman under 18; striking down efforts to expand on laws requiring women to give informed consent before having an abortion; striking down a 24-hour waiting period; and striking down a law requiring doctors to inform women of the risks and of assistance available if she were to carry the fetus to term.

But there have been some notable victories for abortion opponents including a ban on the use of taxpayer funds to finance abortions for low-income women.

And nine years ago, the justices, in a 5-4 ruling, upheld a federal ban on a controversial later-term procedure -- called "partial birth abortion" by its critics -- rejecting concerns the law didn't take into account the physical safety of the woman.

The swing vote, as in previous cases, came from Kennedy. Many court watchers think his vote will prove crucial in the current Texas dispute as well.

Both sides in Wednesday's scheduled one-hour argument will offer familiar, if differing, talking points. 

"The state has wide discretion to pass laws ensuring Texas women are not subject to substandard conditions at abortion facilities," said Texas Attorney General Ken Paxton. "The advancement of the abortion industry's bottom line shouldn't take precedence over women's health."

Abortion rights groups counter the mandate will leave women of reproductive age in the state with minimal health care options

"Over 900,000 Texas women of reproductive age, more than a sixth of all such women in Texas, now reside more than 150 miles from the nearest Texas abortion provider, up from 86,000 prior to the enactment of the challenged act," said the clinics in their petition to the high court. "Women's ability to exercise their constitutional right to obtain an abortion will be lost, and their lives will be permanently and profoundly altered," by having those clinics remaining closed.

The high court case is Whole Woman's Health v. Hellerstedt (15-274). A decision is expected in late June.