More than 100 Tory MPs are expected to call for the ban on new grammar schools to be abolished.
Conservative Voice, a Tory activist group, will formally restart its grammar schools campaign – calling for the new grammar schools to be built – on Tuesday.
The group, started by MPs David Davis and Liam Fox in 2012, will write to Theresa May and education secretary Justine Greening to call for the 1998 law, which bans the creation of new English grammar schools, to be repealed.
The move comes after Ms Greening, who is the first education secretary to attend a comprehensive school, said last week that she was “open minded” to a return to grammar schools.
As MPs break for the summer, the Conservative Voice told the Sunday Telegraph that they plan to launch a social media drive, and host events across the country, to build up pressure.
Don Porter, founder of Conservative Voice, said: “We will be relaunching the grammar schools campaign due to the consistent and considerable interest that we are receiving around the country.
“I am absolutely delighted with the tone, style and content of the new Prime Minister’s agenda. In my view, a fundamental part of social mobility will be the return of grammar schools throughout the country.”
Ms May, who was educated at a grammar school, has previously supported a new grammar school annexe in her constituency of Maidenhead.
Meanwhile, Nick Timothy, Ms May's chief of staff, has been described as “absolutely pro-grammar” and will be instrumental in any plans to undo the ban on new grammars.
The debate on grammar schools is one of the topics covered in this week's TES podcast.