The Prime Minister will warn that politics is under threat from increasing levels of intimidation and abuse.
In a speech next week to mark the centenary of women’s right to vote, Theresa May will urge politicians on all sides to “take a stand for decency, tolerance and respect”.
The Prime Minister will pay tribute to those who braved “open hostility and abuse to win their right”.
And she will warn: “In the 21st Century it cannot be acceptable for any woman – or any person – to have to face threats and intimidation simply because she or he has dared to express a political opinion.
Her speech comes after her own backbencher Jacob Rees-Mogg had to face down aggressive protesters who tried to violently disrupt a public event in Bristol.
Last year, Mrs May launched an investigation after MPs and candidates in the General Election complained of death threats and other forms of intimidation.
The report, published last December, warned women, ethnic minority and gay candidates were more likely to suffer abuse.
In that same month, the PM addressed the commons after Tory MPs who supported an amendment to the Brexit withdrawal bill received death threats.
When Sky News confronted some of those online “trolls” they were reluctant to admit any wrongdoing.
The Prime Minister will say: “In public life, and increasingly in private conversations too, it is becoming harder and harder to conduct any political discussion, on any issue, without it descending into tribalism and rancour.
“Social media and digital forms of communication – which in themselves can and should be forces for good in our democracy – are being exploited and abused, often anonymously.
“British democracy has always been robust and oppositional but a line is crossed when disagreement mutates into intimidation.
“When putting across your point of view becomes trying to exclude and intimidate those with whom you disagree.”
The Prime Minister will add: “It is time we asked ourselves seriously whether we really want it to be like this. Whether we are prepared to accept a permanent coarsening and toxifying of our public debate or whether, together, we will take a stand for decency, tolerance and respect.”
Mrs May will set out Government plans to crack down on intimidation on the campaign trail.
A consultation will be launched on a new offence in electoral law of intimidating parliamentary candidates and their campaigners. The current offence of electoral intimidation relates to undue influence on voters.
And legislation will be brought forward to remove the requirement for candidates standing as councillors in local elections to have their addresses published on ballot papers.
The move would bring local elections in line with UK parliamentary elections where candidates have not been forced to include home addresses on ballot papers since May 2010.