Updated

RICHMOND, Va. -- Virginia took a big step Thursday toward eliminating most of the state's 21 abortion clinics, approving a bill that would likely make rules so strict the medical centers would be forced to close, Democrats and abortion rights supporters said.

Gov. Bob McDonnell, a Republican and Catholic, supports the measure and when he signs it into law, Virginia will become the first state to require clinics that provide first-trimester abortions to meet the same standards as hospitals. The requirements could include anything from expensive structural changes like widening hallways to increased training and mandatory equipment the clinics currently don't have.

While abortion providers must be licensed in Virginia, the clinics resemble dentists' offices and are considered physicians offices, similar to those that provide plastic and corrective eye surgeries, colonoscopies and a host of other medical procedures.

Democrats and abortion rights supporters said the change would put an estimated 17 of the state's 21 clinics out of business. Most of the clinics also provide birth control, cancer screenings and other women's health services.

"This is not about safety for women. This is about ideology, and this is about politics," said Tarina Keene, executive director of NARAL Pro-Choice Virginia. "The women of the commonwealth are going to be the ones left to suffer."

Abortion rights supporters warned of legal challenges while supporters heralded it as a way to make the procedures safer.

"It is not about banning abortions," said Sen. Jill Vogel, R-Winchester. "It is simply caring for women who are about to have an invasive surgical procedure and creating an environment for them where they have the opportunity to do that in a place that is safe."

No other state requires clinics that provide early abortions to meet hospital standards.

Nineteen states, including Virginia, require an abortion to be performed in a hospital after 12 weeks, according to the Guttmacher Institute, which tracks abortions and laws concerning the procedures.

More than 27,000 of the 28,000 abortions performed each year in Virginia are completed during the first-trimester, Keene said.

"Does Virginia really want to take the lead in such obstruction?" asked Sen. Maime Locke, D-Hampton, who called the bill "draconian and patriarchal at best."

Democrats argued it wouldn't pass constitutional muster because it would put an undue burden on poor women and those in rural areas, where clinics likely would close. They also argued it would violate the equal protection guarantees of the Constitution by treating abortions differently than similar procedures.

"Absolutely all that will be accomplished by this vote is to restrict access to a safe and legal procedure to poor women," said Sen. Mary Margaret Whipple, D-Arlington. "This does nothing to end abortions. It is purely discriminatory. It makes me heartsick."

Laurence H. Tribe, professor of constitutional law at Harvard Law School, said the bill would likely be deemed unconstitutional "because its transparent purpose and effect would be to make such early abortions far more difficult if not impossible for many women to obtain."

Attorney General Ken Cuccinelli, who supported similar legislation as a state senator, said he believes the law would be constitutional.

"For over 25 years, Virginia abortion clinics have not been held to minimal health and safety standards," he said. "As a result, women who walk into these clinics are often not treated with the care and respect that any human being deserves."

Anti-abortion bills typically die in a Democrat-controlled Senate committee, but Republicans in the House tacked it onto a bill that already had passed the Senate. Doing so allowed the bill to sidestep the committee and forced a vote on the Senate floor, where Democrats hold a 22-18 majority.

Two anti-abortion Democrats voted with Republicans, and Lt. Gov. Bill Bolling, a Republican, cast the tie-breaking vote after hours of debate.

After it becomes law in July, the state Board of Health will take public comments before issuing the guidelines. The board is appointed by the governor.