The man accused of murdering British lawmaker Jo Cox gave his name as "Death to traitors, freedom for Britain" in court Saturday, following the killing that has brought campaigning ahead of the country's EU referendum to a standstill.

Thomas Mair, 52, made his defiant statement as he made his first appearance in Westminster Magistrates' Court in London after being charged overnight with the murder of the popular Labour Party lawmaker.

Mair refused to give his correct name and did not answer when asked for his address and date of birth.

Labour Party lawmaker Cox, 41, was shot and stabbed to death Thursday after getting out of her car in the town of Birstall in her home constituency.

The rare killing in broad daylight of a British politician has stunned the country and silenced what had been a furious campaign ahead of Thursday's referendum on whether Britain should remain in the European Union.

Both sides suspended campaigning as a sign of respect for Cox, who became the first sitting member of Parliament to be killed in a quarter-century.

Major campaign events and rallies are not expected to resume until Monday or later, but there were signs Saturday of low-level campaigning being reactivated, with the "leave" campaign adding new posts to its Twitter feed.

Time is running out, and analysts say they expect the campaign tone to be more conciliatory and less confrontational when it resumes.

It is not clear what, if any, impact the killing of Cox may have on the referendum vote, which is expected by many observers to be close.

Mair was charged with murder, inflicting grievous bodily harm, possession of a firearm with intent to commit a crime, and other gun-related charges.

Deputy Chief Magistrate Emma Arbuthnot said in court that a psychiatric report should be prepared "bearing in mind the name he has just given."

Mair will be kept in custody at Belmarsh Prison until his next court appearance, set for Monday at the Old Bailey courthouse.

He was not required to enter a plea during the brief session Saturday, during which he was handcuffed to a guard throughout the proceedings.

Authorities have not offered a motive for the killing. Counter-terrorism police were involved in the investigation looking for possible links, but the charges filed did not include terrorism offenses.

Cox was a former aid worker who championed immigrant rights, bringing an end to Syria's civil war and keeping the United Kingdom in the European Union. The day before her killing, Cox joined her husband and two young children in campaigning for the pro-EU cause on the River Thames, where the family had lived in a houseboat since her election last year.

Vigils have been held across the country in her memory and Parliament has been recalled Monday to honor her.

U.S. President Barack Obama telephoned her husband from Air Force One to express condolences and released a statement praising her commitment and service.

"The president noted that the world is a better place because of her selfless service to others, and that there can be no justification for this heinous crime, which robbed a family, a community, and a nation of a dedicated wife, mother, and public servant," the White House statement said.

Police have praised the bravery of a 77-year-old man who tried to aid Cox during the attack and was seriously injured. The man is recovering in hospital.

The attack has raised security concerns for other members of Parliament who routinely meet with constituents in public meetings.

It has long been a tradition in Britain for lawmakers to hold regular "surgeries" in which they discuss local, national and international issues with residents of their district.