It’s been a little more than two years since the last time women in Saudi Arabia campaigned for the right to drive. Now activists are calling for women to get behind the wheel again Saturday, and they hope reforms made by the monarchy since then have readied the deeply conservative nation for change.

The reforms made by King Abdullah in recent years have been cautious, showing his wariness of pushing too hard against influential ultraconservatives. But given the overwhelming restrictions on women in the kingdom, where the strict interpretation of Islam known as Wahhabism is effectively the law of the land, even the tiny openings have had a resounding effect.

Perhaps one sign of the impact of the changes is the loudness of the backlash by conservatives against Saturday’s driving campaign.

Around 150 clerics rallied outside one of the king’s palaces this week, some accusing Abdullah’s top ally — the United States — of being behind calls to let women drive. A prominent cleric caused a stir when he said last month that medical studies show that driving a car harms a woman’s ovaries. Those opposed to the campaign have also used social media to attack women activists or have urged people to harass female drivers.

The government has given mixed signals about how it will deal with the campaign, illustrated by a statement put out this week by the Interior Ministry, which is in charge of police.

The ministry warned against marches or gatherings under the pretext of the driving campaign. It said violators “disturbing public peace” will be dealt with firmly.

But activists have interpreted the statement to mean that police will crack down on men who try and attack or harass women drivers, said Hatoon al-Fassi, a Women’s History professor at King Saud University in Riyadh. She pointed out that women have made clear they aren’t holding gatherings Saturday; women will simply drive in a show of defiance of the ban, perhaps on the pretext of running errands.

“We are feeling a more positive environment. There is a general atmosphere of acceptance,” al-Fassi said. “The public is positive and the reactions on social media are beautiful.”

Still, the statement’s language also caters to conservatives because it harkens back to charges of “violating public order” that were levied against a female driver arrested in 2011.

In a sign authorities do not want the driving campaign to grow too bold, police have privately told the campaigners not to speak to the media, according to one activist who wished to remain anonymous for fear of retribution.

The first major driving protest came in 1995 and was met by a heavy response. About 50 women who drove their cars were jailed for a day, had their passports confiscated and lost their jobs.

In June 2011, about 40 women got behind the wheel and drove in several cities in a protest sparked when a woman was arrested after posting a video of herself driving. Individual women continued to defy the ban, and one woman was arrested and sentenced to 10 lashes. The king overturned the sentence.

For Saturday, campaigners hope to bring out bigger numbers. They claim to have 16,000 signatures on a petition of support, a quarter more than in 2011. This time, they say they understand the laws better and have the full support of male relatives, and they argue public attitudes are changing.

They have posted online videos of themselves driving in recent weeks, with some showing passing male drivers giving them a thumbs-up in support. State newspapers have published articles and opinion pieces almost daily on the debate, something impossible only a few years ago.