In the past six weeks, four states – Alabama, Arkansas, Kansas and North Dakota – have adopted some of the most stringent restrictions on abortion in the nation. On Friday, Virginia may join the list when the state’s Board of Health votes on whether to require abortion clinics to meet hospital standards on a permanent basis.

This flurry of activity on the state level has provided abortion opponents with fresh energy and optimism while their foes vow to challenge the laws in court. Even as Americans have moved left on some social issues, such as same-sex marriage and marijuana legalization, conservatives have gained significant ground in the states when it comes to abortion.

“The grass-roots momentum is really playing out electorally,” said Susan B. Anthony List spokeswoman Mallory Quigley, whose organization works to elect politicians opposed to abortion.

The trend marks a contrast with last fall, when GOP Senate candidates Todd Akin of Missouri and Richard Mourdock of Indiana made controversial remarks about pregnancies stemming from rape, mobilizing support for Democrats.

But in the states, Republicans had another banner election year, making it easier for abortion opponents to enact restrictions. There are 23 states where Republicans now control the governorship and the state legislature, compared with 14 where Democrats hold such an advantage.

“The states have become very polarized,” said Glen Bolger, a GOP pollster and partner in Public Opinion Strategies. “They’re either the reddest of red or the bluest of blue, so whether you’re a Republican or a Democrat, you can advance your social agenda.”

Unlike attitudes on same-sex marriage, which have shifted rapidly in recent years, Americans’ views on abortion have remained largely unchanged since the 1990s. Fifty-five percent of respondents said abortion should be legal in all or most cases in an August 2012 Washington Post-Kaiser Family Foundation poll, with just over four in 10 saying it should be illegal in all or most cases.

While states adopted a high number of abortion restrictions in both 2011 and 2012, the nature of the laws enacted this year is different, activists say. In Arkansas, the state legislature overrode the governor’s veto last month to ban abortions starting at 12 weeks. On Tuesday, North Dakota Gov. Jack Dalrymple signed legislation to prohibit abortion as soon as a fetal heartbeat is detected, which can be as early as six weeks. That same day, Alabama Gov. Robert Bentley signed a law requiring doctors providing abortions to have admitting privileges at a local hospital.

The Kansas legislature passed a measure last week that says life begins at fertilization, bars tax breaks for abortion providers and prohibits abortions based on sex selection. Gov. Sam Brownback, a Republican, has pledged to sign the measure.

Jennifer Dalven, who directs the ACLU’s Reproductive Freedom Project, said “these laws are much more extreme. To make it increasingly impossible for women to gain access to safe abortion, they’ve jumped to their endgame.”

Abortion opponents, by contrast, said they’ve experienced a groundswell of support in light of recent controversies over abortion clinic conditions. Philadelphia abortion provider Kermit Gosnell is now on trial, charged with killing seven newborns and one adult female patient.

The Virginia rules could force abortion providers to undertake expensive physical renovations, including widening hallways and doorways and installing new heating and ventilation systems to meet specific requirements.