As Republicans prepared to battle Barack Obama’s re-election in 2011, Matthew Whitaker bounded on to a stage in Washington to rally the party’s troops on the “culture wars” between conservatives and liberals on social policy.

“They’re not over,” Whitaker assured his audience, at an event convened by Steve King, the rightwing Iowa congressman. “We’re still fighting.”

Whitaker and his allies lost ensuing battles on issues such as same-sex marriage. But civil rights activists fear that having now been installed as Donald Trump’s acting attorney general, Whitaker is readying a counterattack.

A review by the Guardian of previously unreported remarks revealed Whitaker has advocated for hardline anti-abortion policies that would drastically reshape laws affecting American women seeking to terminate a pregnancy.

Whitaker, a conservative Christian, endorsed “personhood” bills that would effectively outlaw abortion, and said as a Senate candidate that he would spend every day in Washington pushing anti-abortion policy.

He also once said that as a federal prosecutor, he personally disagreed with having to use a clinic protection law against a man who crashed his car into a women’s health facility and tried to set it on fire while complaining about abortion.

The comments position Whitaker, a conservative Christian, as an even more forceful opponent of abortion than his predecessor, Jeff Sessions, whose own record on the issue raised concerns among abortion rights advocates.

Adrienne Kimmell, the vice president of Naral, which advocates against restrictions on abortion, said Trump and Whitaker posed a threat to women’s ability to obtain terminations and access other health services.

“This administration is putting people in positions of power, with the ability to impact policies that have massive consequences for women and families, who hold anti-choice, dangerous beliefs that undermine women’s lives and ability to access reproductive healthcare,” she said.

A justice department spokeswoman did not respond to a request for comment.

Whitaker, 49, has been frank about the strength of his religious views. In 2014, as a private attorney in Iowa representing an editor fired for writing homophobic blog posts, Whitaker told a radio interviewer: “We’re all poor, miserable sinners … without a saviour we’re all doomed to eternal damnation.”

Earlier that year, Whitaker said judges needed a “biblical view of justice” and raised doubts about the judgment of non-religious lawyers. In 2007, as US attorney for Iowa’s southern district, Whitaker was ordered by justice department officials in Washington to pull out of a planned appearance hosting an event for the Iowa Christian Alliance.

While seeking the Iowa Republican party’s US Senate nomination in 2014, Whitaker told a group of college students he was “100% pro-life” and supported a bill proposed by Senator Rand Paul of Kentucky that would grant constitutional protections to fetuses the moment they were conceived, effectively outlawing abortion. Video footage of the event was viewed by the Guardian.

“I don’t want to criminalise females who find themselves in crisis. But at the same time, I do believe life begins at conception,” Whitaker said at the time.

Campaigning for the presidency in 2016, Trump restyled himself as an anti-abortion conservative and said women should be punished for having abortions. He has appointed dozens of anti-abortion judges to the federal judiciary, including Neil Gorsuch and Brett Kavanaugh to the US supreme court.

In another comment made before his rise to national prominence, Whitaker signalled a personal objection to a federal law prohibiting the use of force and intimidation to stop women using reproductive health services, which was passed almost 25 years ago after a wave of attacks by anti-abortion extremists culminated in the murder of a doctor in Florida.

Speaking in 2011, Whitaker said he would enforce the Freedom of Access to Clinic Entrances (Face) Act despite his beliefs. But activists said they feared incidents would go unpunished under his leadership of the justice department. Helene Krasnoff, Planned Parenthood’s vice-president for public policy, said: “No one should face violence, harassment or intimidation when accessing healthcare.”

Whitaker mentioned his objection to the Face Act during an interview by a selection panel for Iowa’s state supreme court, in February 2011. The panel reportedly received letters of complaint about Whitaker and did not select him as a finalist.

He was asked by a panel member to give an example of a situation when he had been challenged by “a difference between your personally held beliefs and what your duties were as an officer of the court or an officer of the country”.

Whitaker said: “We had a unique case in south-east Iowa where an individual put his car into a family planning clinic,” and went on to explain that his office found the driver had violated the Face Act.

“So that’s one clear example where my own personal beliefs may be inconsistent but I had no problem following the law and enforcing the law,” he said.

The case Whitaker cited appeared to be that of David McMenemy, a man prosecuted by Whitaker’s office for driving into Edgerton Women’s Health Care Center in 2006 and trying to set it on fire. McMenemy told police he attacked the clinic because he believed, wrongly, that it performed abortions.

Whitaker did not elaborate on the grounds for his opposition to the law. Some opponents have claimed the law encroaches on the constitutional rights of anti-abortion activists to protest outside clinics.

According to court records, McMenemy was not, in fact, prosecuted under the Face Act. “In reviewing the indictment, it appears Mr McMenemy was only charged under the federal arson statute,” Rachel Scherle, a prosecutor in Iowa’s southern district, said in an email. McMenemy pleaded guilty and was sentenced to five years in prison.

In any case, pro-choice campaigners expressed concern that Whitaker objected to a law intended to protect the physical safety of medics and patients and outlawing the destruction of reproductive health clinics.

“It’s a very disturbing view, but it is consistent with anti-choice sentiment among many ultra-conservative people,” said the Rev Katherine Ragsdale, the interim president and chief executive of the National Abortion Federation.

The Face Act was signed by President Bill Clinton in May 1994. The law was supported by 18 Republicans, including Senator Mitch McConnell of Kentucky, who is now the majority leader.

Within months of becoming law, the Face Act was used to prosecute Paul Hill, who murdered a doctor and his bodyguard in Florida. The US supreme court declined several times to hear challenges to the legality of the law. Pro-choice campaigners credited the law with a sharp decline in violent attacks against clinics.

According to data compiled by the National Abortion Federation, there was a spike in hostile actions against abortion providers during the first year of Trump’s presidency. The group said reports of obstruction and trespassing more than tripled compared with 2016, while reported death threats and threats of harm almost doubled.

In August last year, a group of Democratic senators urged Sessions to enforce the Face Act to counter the increase in threats. Three people were shot dead at a Planned Parenthood clinic in Colorado in November 2015.

Speaking to an interviewer during his Senate nomination campaign, Whitaker also said he would spend “every day” in Washington trying to advance the pro-life cause.

“I’m very concerned that as we continue to erode life and life becomes under constant challenges from the left, that we need to make sure we’re defending it,” Whitaker said.