Members of Rathgeber's Edmonton-St. Albert Conservative Association voted to cut ties with the MP and said they want to take steps immediately to find a new Conservative candidate.
"The board was surprised and caught off guard by Brent's decision," association president Darren Bieganek said in an interview.
"We're disappointed with his decision to resign from caucus."
Bieganek said the association's executive members met Friday morning and reached the decision unanimously.
Rathgeber quit the Tory caucus late Wednesday night. He said government backbenchers had become "trained seals" that carry out the wishes of unelected officials in Prime Minister Stephen Harper's office.
In a prepared statement issued Friday, the association disagreed.
"The (association) expresses its full support for the policies of the Conservative Party of Canada and its full support for the party’s leader, Prime Minister Stephen Harper," read the news release.
Bieganek said the association is asking senior Conservative party officials to get nominations going as quickly as possible so there's a candidate ready to go for the next election, or, if Rathgeber steps down earlier, for a byelection.
Members are not insisting that Rathgeber step down before a general election, Bieganek said. Part of the reason for that is voter fatigue.
"Our belief is the citizens of the riding are probably not interested in having an election right now.
"We've had three federal elections in the last six years. We had a provincial election last year and we've got a municipal election coming up in October."
Rathgeber, 48, has said he has no plans to resign his seat to force a byelection and, if he does run in the next general election, it is likely to be as an Independent.
The riding association's decision does not affect the running of Rathgeber's office, which is financed by Parliament.
Rathgeber announced on Twitter that he was quitting caucus over a lack of government transparency and other concerns.
He said the trigger was the government's decision to water down his private member's bill to expose the salaries of senior federal civil servants.
If passed, the bill would have raised the transparency bar for salary disclosure to $188,000. The committee reviewing the legislation instead decided to raise the threshold to more than $400,000.
Rathgeber said Conservative members on the committee were ordered by PMO staff to raise the threshold, even though not one witness to the committee recommended it. He also said the executive arm of government, through the unelected employees in Harper's office, is increasingly dictating the legislative agenda to MPs in a way that leaves no room for dissent in public or behind closed doors.
Rathgeber was first elected to the Commons in 2008 and was re-elected in 2011.
Bieganek said he had yet to speak to Rathgeber, but suggested that the MP may have made his job to serve constituents that much harder.
"I anticipate that it may be more difficult for him to get things accomplished sitting as an Independent than if he were a member of the government."
Rathgeber's adviser, Joe Becigneul, said the Conservative association decision was expected. "That would just be standard," he said.
Becigneul said Rathgeber's decision came within hours of his private member's bill being "gutted."
"Brent didn't come to the decision any quicker and they (the riding association members) were the first people to be notified."
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