The decision to give the activist at the centre of the Tory bullying scandal a formal role was approved by the party's senior management team.
BBC Newsnight has learned that both party chairmen and election chief Lynton Crosby were on the board which agreed to appoint Mark Clarke and fund his campaign.
It has also emerged that Grant Shapps, then Tory co-chair, personally read a highly critical report on Mr Clarke's behaviour during the 2010 election before agreeing to back Mr Clarke.
Mr Clarke denies all the allegations against him.
The Conservatives have been under mounting pressure to explain why Mr Clarke was embraced by the party in 2014, despite having been struck off the list of approved Tory candidates after a number of complaints were made about his behaviour during his 2010 campaign in the south London constituency of Tooting.
The party has been engulfed by allegations of bullying, sexual harassment and blackmail since a young activist, Elliott Johnson, took his life in September, having previously complained he was being bullied by Mr Clarke. The decision to give the activist at the centre of the Tory bullying scandal a formal role was approved by the party's senior management team.
One former activist told Newsnight Mr Clarke had sexually harassed and then threatened her. The programme spoke to five more activists who say they made complaints about Mr Clarke.
Mr Clarke strongly refutes all allegations of bullying, harassment, assault or attempted blackmail.
Newsnight understands that in mid-2014, the party's senior management group, made up of co-chairs Grant Shapps and Lord Feldman, as well as Mr Crosby and deputy chairman Stephen Gilbert, discussed whether the party should work with RoadTrip, the organisation Mr Clarke had set up to bus young volunteers around the country.
The party bosses had concerns over Mr Clarke's reputation. "No-one didn't know that he had been a bit of a prat as a candidate," said one source familiar with the discussion. "The question was do we want them doing their thing all over the country or do we want them going to seats we are targeting?"
Mr Shapps is understood to have read the official report on Mr Clarke written after the 2010 election and concluded that it contained evidence that Mr Clarke had been rude and lazy, but that the report did not include more serious allegations such as bullying, harassment or blackmail.
This account of the candidate report appears to conflict with that of another party worker who previously told Newsnight that his submission to the report included a complaint about "extreme aggressive behaviour, verging on violence".
Newsnight understands that Mr Shapps decided to recommend taking Mr Clarke back into the fold after meeting him and being persuaded that Mr Clarke was a reformed character.
The senior team subsequently agreed to co-ordinate campaigning efforts with Mr Clarke and give him the title of Director of RoadTrip, according to a source familiar with the issue. "Grant wrote the letter but everyone took the decision."
It's understood that Grant Shapps also approved a Conservative Campaign Headquarters (CCHQ) pass for Mr Clarke.
In an article written for ConservativeHome in August 2014, Mr Clarke wrote: "Grant, who always believed in what we were trying to do, ensured that we had the full support of Team2015 and CCHQ."
He also boasted of how he had been given access to the Team 2015 database of activists: "I was sceptical of the Team 2015 database [at CCHQ] until I used it. There are thousands of names of people willing to help and linked to seats… We find that 25 per cent of our attendees come from that database."
Asked about whether the senior management team had approved the decision to bring in Mr Clarke a Conservative spokeswoman said on Monday: "In 2014, Grant Shapps asked Mark Clarke to work in conjunction with the Party's Team 2015 [the Party's own volunteer activist organisation]."
She said the decision to fund RoadTrip had been taken by the senior management team.
The disclosure that other senior party figures were involved in the decision to rehabilitate Mr Clarke will put pressure on current chairman Lord Feldman who has maintained he was unaware of any allegations against Mr Clarke until August when he ordered an internal inquiry.
Tory MP Ben Howlett told Newsnight last week that he raised concerns about Mr Clarke with both Lord Feldman and Baroness Warsi, party chair between 2010 and 2012, as well as with Mr Shapps's office.
However it's understood that Mr Shapps maintains he did not receive any serious complaints about Mr Clarke while serving as party co-chair until May 2015.
James Clayton and Esther Oxford were reporting for BBC Newsnight. Watch their full report into the Tory bullying scandal here.