A new law that requires Virginia’s Board of Health to regulate abortion clinics will go into effect just as appointees of Gov. Robert F. Mc­Don­nell assume a majority on the panel, offering the Republican governor expansive power to shape clinic rules.

Already, Mc­Don­nell, a longtime opponent of abortion, has appointed six of the board’s 14 members. In coming months, he will name the board’s 15th member, filling a vacancy, and replace another member whose term ends June 30.

With those actions, McDonnell’s eight appointments will outnumber board members chosen by former governor Timothy M. Kaine (D).

The shift will occur just as the board considers controversial new rules for clinics that antiabortion activists have said will make the facilities safer, but that clinic operators and abortion rights supporters fear could force many to close.

McDonnell’s hand will also be strengthened by a relatively fast process for writing the rules, which gives the Board of Health just one opportunity to vote on emergency regulations that go into effect Jan. 1 and last for up to 18 months.

The quick process is necessary, Health Commissioner Karen Remley explained to the Board of Health on Friday, because a bill adopted by the General Assembly last month requires new rules to be written within 280 days.

Even after the board votes in September, Mc­Don­nell, in consultation with Attorney General Ken Cuccinelli II (R), can rewrite the rules before they go into effect next year.

The emergency guidelines will be in place while the board embarks on a more deliberative two-year process for formulating permanent rules.

Mc­Don­nell spokesman J. Tucker Martin said Friday that the governor seeks regulations that ensure “the safety and welfare of individuals who visit one of these outpatient facilities.”

He said that clinic rules will be vetted similarly to other regulations that require input from the administration, but that it’s “premature” to discuss whether he would make revisions to what the Board of Health adopts.

But abortion rights activists say they fear that Mc­Don­nell will seek to make abortion clinics, now treated like doctor’s offices, follow rules imposed on ambulatory surgical centers. Those include guidelines about the width of hallways that they believe could force as many as 17 of Virginia’s 21 clinics to close, they have said.

“The governor can have just as much power over this as he wants to,” said Tarina Keene, executive director of NARAL Pro-Choice Virginia, one of several groups that have threatened litigation if the regulations reduce access to abortions.

The politically mixed Board of Health is typically given broad deference in health regulatory issues in Virginia, which has left both sides in the abortion debate scrambling to learn more about its members.

They will find that one member appointed by Mc­Don­nell this year has been a donor to the Family Foundation, the state’s leading antiabortion group. The wife of another member years ago attended an abortion rights rally on the Mall with a Democratic state senator. That board member received appointments from Kaine and Mark Warner (D-Va.), who served as governor before becoming a U.S. senator.

Members are appointed for up to two four-year terms, and most seats are required by law to be held by members of professional health organizations, such as the Medical Society of Virginia, the Virginia Pharmacists Association and the Virginia Nurses Association. Former colleagues and others say they’re uncertain about many members’ positions on abortion.

“It was a very professional, collegial board,” said Arlington County Board member Barbara A. Favola, a Democrat who served on the board until last year alongside several current members. “We didn’t view ourselves as partisan, and I didn’t know anyone’s political persuasion.”

Mc­Don­nell’s six appointments to the board so far include a doctor based in Virginia Beach who works for a major health insurance company; a human resources specialist from Fairfax; the chief executive of a Danville hospital; and a pediatrician who is also the vice mayor of Chesapeake.

Mc­Don­nell also reappointed Charles K. Johnson, a dentist from Richmond first named to the board by Kaine. And he named former Richmond resident Gail Taylor as a consumer representative. Family Foundation President Victoria Cobb confirmed that Taylor has been a donor and supporter of the group.

Mc­Don­nell administration officials said they prioritize finding candidates whose backgrounds and temperaments make them qualified to serve on boards. They also look for candidates who generally agree with McDonnell’s governing philosophy, and they sometimes examine potential appointees’ campaign-giving histories.

“The governor will appoint individuals who understand the issues facing the board, are well-qualified and recognized as leaders in their fields, and who are committed to upholding the laws of Virginia,” Martin said.

He would not say whether the administration weighs appointees’ views on abortion.

Both sides in the debate praised the impartiality of the health professionals who serve on the Board of Health, which has vast oversight over everything from drinking water to vital health records to medical examiners’ offices.

Cobb called them a group “well equipped to make thoughtful decisions” geared to making clinics safer and said predictions about the impact of new rules have been overblown.

Most of the board’s 14 members did not return calls or declined to comment about their service this week, including Taylor.

Northern Virginia real estate developer James H. Edmondson Jr., who was first appointed by Warner and will serve into 2013, said the board will conduct a deliberative process, guided by staff and by strict procedural rules.

Edmondson described himself as a “loyal Democrat” and chuckled when reminded that his wife, more than two decades ago, carpooled with now-state Sen. Janet D.Howell (D-Fairfax) to a rally in Washington to support abortion rights. “My wife and I are certainly on the same wavelength on the issue,” he said.

But, he quickly added, “Our first job on the Board of Health will be to follow the law. . . . How it will come out, I just don’t know.”

H. Anna Jeng, an environmental health professor at Old Dominion University who was appointed by Kaine as a representative of public health groups, said Friday that she hopes to “strike a balance” between protecting women’s health and not placing an “undue burden” on clinics.

Both sides in the debate said they will watch McDonnell’s remaining appointments to the body closely, as will Democrats in the General Assembly who will have the opportunity to confirm appointments next year.

Some close observers of the Health Board said the group may prove unpredictable.

“This is a controversial issue,” said Michael Jurgensen, senior vice president of health policy for the Medical Society of Virginia, whose members by law must hold two seats on the board. “But the board, to the extent that they can, will try to look to their charge — which is to write the regulations absent consideration of the controversy.”