Taoiseach and party leader Enda Kenny also had serious questions to answer about the campaign, he said.
Ahead of what will be a critical meeting for Mr Kenny today with his TDs, Mr Shatter said it was up to the parliamentary members whether he should remain as leader.
During an interview with RTÉ’s Sean O’Rourke, Mr Shatter said the party had intervened in his Dublin-Rathdown constituency and effectively lost him his seat.
“For Fine Gael members, there is an issue around the election messaging, the obsession with focus groups and marketing, the use of outside consultants, an incapacity during the course of that campaign to recognise that things are going wrong.”
Mr Shatter said previously there were local vote management issues in constituencies but headquarters “imposed” an arrangement which lost him his seat and got Stillorgan-based councillor Josepha Madigan elected. He had warned about the strategy being used, just days prior to polling.
“My views were entirely ignored. Those sitting in Mount Street or elsewhere in Fine Gael headquarters can’t be gazing into a crystal ball deluding themselves as to what they expect might happen and then giving directions that have no reality,” he said.
He said there was a problem about “the praetorian guard” about the party and non-elected officials, engaged in the campaign.
The new parliamentary party needed to have a full examination of how the campaign went wrong, he said.
Mr Shatter said the problem was the focus had been on “strategy and messaging” and not on people.
“For the first week of the campaign, we all got lost in ‘fiscal space’. That was the most bizarre commencement of a campaign I’ve seen in all my 30 years in politics. The message became instantly confused. Clearly, the Taoiseach has serious questions to ask himself and to answer about the manner in which the campaign was conducted,” he said.
Health Minister James Reilly, who lost his seat in Dublin-Fingal, said he had raised concerns about the campaign and the need to “humanise” its message which he claimed had failed to connect emotionally with people. “Campaigns are very noisy and it’s hard to get a look in,” he said.