Bergen said in a statement late Wednesday that Fast informed her he will be "stepping away from his duties."
"Ed has publicly stated his support for one of the Conservative Party of Canada’s leadership candidates and would like to be able to offer more dedicated support to that team," Bergen said.
Fast is co-chairing the leadership campaign of former Quebec premier Jean Charest. On Wednesday the pair panned Charest's leadership rival Pierre Poilievre for saying he would fire the Bank of Canada governor.
Fast said he believes Poilievre's pitch to fire Tiff Macklem over the country's inflation rate, which is the highest it’s been in 30 years, hurts the party’s credibility on economic issues.
Poilievre pledged to replace Macklem as the head of the country's central bank during last week's leadership debate in Edmonton, saying he would put someone in his place that follows its low-inflation mandate.
"I'm deeply troubled by suggestions by one of our leadership candidates, that that candidate would be prepared to interfere already at this stage in the independence of our central bank," Fast told reporters ahead of the party's caucus meeting.
"We lose some credibility when we do this … It is fair to ask questions, to demand solutions to the skyrocketing cost of living. But we also have to respect the institutions that have been granted independence to ensure that they function apart from political interference."
Fast was appointed as the party's finance critic by interim Conservative leader Candice Bergen after Poilievre, the previous critic who spent months laser-focused on inflation, decided to enter the contest.
Bergen plans to announce a new finance critic "shortly," and said Fast is still a valued member of the caucus.
@HonEdFast out as Tory finance critic after criticizing leadership candidate @PierrePoilievre. #ConservativeLeadership #CPC #CDNPoli
Charest's campaign spokeswoman, Michelle Coates Mather, called the news disheartening and said the team is "incredibly proud" to have his expertise on the campaign.
In a statement, Mather said Fast "spoke out to voice legitimate concerns against policies he felt would hurt the Canadian economy, investor confidence, and the market."
Fast attributes inflation, which is driving up the cost of everyday goods like gas and groceries, to government spending. Experts say other factors are also at play, including how countries are still dealing with pandemic-related supply chain issues and Russia's invasion of Ukraine.
"Central banks around the world have struggled with the same challenges that our central bank has struggled with," he said.
Macklem was appointed in 2020 to serve a seven-year term.
Poilievre has dismissed previous criticism of his proposal to fire the central bank governor as merely political elites attacking his message.
He stuck to that theme in his response on Wednesday, saying the Bank of Canada governor has a mandate to keep inflation at two per cent.
"Ed Fast and Jean Charest would have no problem firing a waitress or welder for not doing their jobs. But they won't do the same for a big shot banker whose failures have cost our people a fortune," Poilievre said in a statement.
Earlier in the day, Marilyn Gladu, an Ontario MP who is co-chairing Poilievre's campaign in that province, offered a similar defence of his proposal to axe Macklem. She also supported his embrace of the cryptocurrency Bitcoin as a way to deal with inflation, which has been dismissed by other leadership candidates as irresponsible and financial experts as simply untrue.
"The more the Liberal media gets excited and upset about Pierre Poilievre, the more I know that they're worried he's going to win."
She didn't appear, however, to endorse his idea to fire Macklem. Gladu said she prefers to work with the central bank to ensure it follows its mandate of keeping inflation low, down from the 6.8 per cent that it hit in April.
"I think in the heat of the leadership race everybody has ideas, but the reality is it's the Bank of Canada's mandate, we need to see that done. I will give my input to the leader as we move on," Gladu said.
Gerard Deltell, a high-profile Quebec MP who had been among representatives from that province encouraging Charest to run, said Wednesday that leadership races are all about the exchange of ideas, including bold, out-of-the-box ones that not everyone agrees with.
"In this specific case, I disagree with Mr. Poilievre."
This report by The Canadian Press was first published May 18, 2022.