Barack Obama has drawn criticism for accepting an invitation to speak at a Wall Street conference for almost half a million dollars.

The former President will receive $400,000, equal to his annual pay as President, for a speech at Cantor Fitzgerald's healthcare conference as a keynote speaker in September.

Mr Obama's fee is nearly twice as much as Hillary Clinton has charged private companies for similar events.

The former President, who called bank CEO’s “fat cats” in the opening weeks of his administration, has come under fire for the Wall Street speech since reports first emerged earlier in the week.

Bernie Sanders has said he thinks it is “unfortunate” Mr Obama opted to receive the fee and argued the decision signifies the profound influence big business has on the political system.

“I think it just speaks to the power of Wall Street and the influence of big money in the political process,” the Democrat Vermont senator told Bloomberg.

“I think it’s unfortunate. President Obama is now a private citizen and he can do anything he wants to but I think it’s unfortunate. You have the former president of Goldman Sachs is now the chief financial advisor for President Trump, and then you have this, so I think it’s unfortunate”.

Michelle Obama as the First Lady Show all 11 1 /11 Michelle Obama as the First Lady Michelle Obama as the First Lady NEW YORK - MARCH 9: Michelle Obama, wife of Presidential candidate Senator Barack Obama (D-IL) addresses the crowd at a fundraising event at the Grand Hyatt March 9, 2007 in New York City. The mass fundraiser of Senator Barack Obama targeted a youthful demographic. (Photo by Michael Nagle/Getty Images) Getty Michelle Obama as the First Lady WASHINGTON - JANUARY 4: U.S. Senator Barack Obama (D-IL) (2nd L) poses for with his wife Michelle (2nd R), Vice President Dick Cheney (R), daughters (C) Malia and Sasha during the reenactment of a swearing -in ceremony on Capitol Hill January 4, 2005 in Washington, DC. The 109th Congress was sworn in January 4. (Photo by Alex Wong/Getty Images) Getty Michelle Obama as the First Lady LOS ANGELES, CA - MARCH 19: Senator Barack Obama and his wife Michelle arrive at the 36th NAACP Image Awards at the Dorothy Chandler Pavilion on March 19, 2005 in Los Angeles, California. (Photo by Frederick M. Brown/Getty Images) Getty Michelle Obama as the First Lady AMES, IA - FEBRUARY 11: Michelle Obama, wife of Senator Barack Obama (D-IL), listens with her daughter Sasha as the Senator addresses a crowd gathered at a campaign rally at Iowa State University February 11, 2007 in Ames, Iowa. Obama is wrapping up a two-day campaign swing through Iowa after announcing February 10, that he would seek the Democratic nomination for President. (Photo by Scott Olson/Getty Images) Getty Michelle Obama as the First Lady DES MOINES, IA - DECEMBER 08: Michelle Obama (L) and talk show host Oprah Winfrey embrace at a rally for Democratic presidential hopeful Barack Obama December 8, 2007 in Des Moines, Iowa. Obama and Winfrey are scheduled to make two stops in Iowa before heading off to campaign events in South Carolina and New Hampshire tomorrow. (Photo by Scott Olson/Getty Images) Getty Michelle Obama as the First Lady CHICAGO - FEBRUARY 05: Michelle Obama, wife of Democratic presidential hopeful Sen. Barack Obama (D-IL), arrives for a Super Tuesday event at the Hyatt Hotel Feburary 5, 2008 in Chicago, Illinois. Polls showed Obama and his rival for the Democratic nomination, Sen. Hillary Clinton (D-NY), in a virtual tie going into Super Tuesday, where primaries and caucuses are held in 24 states. (Photo by Chip Somodevilla/Getty Images) Getty Michelle Obama as the First Lady US President Barack Obama (L) and his wife Michelle (2nd L) meet with Britain's Queen Elizabeth II (2nd R) and Prince Philip, the Duke of Edinburgh (R) during an audience at Buckingham Palace in London, on April 1, 2009. US President Barack Obama visited Queen Elizabeth II at Buckingham Palace on Wednesday while his in London for the G20 summit. Obama and wife Michelle were hosted by the queen for a meeting, the day before the crunch summit on tackling the world economic crisis. AFP PHOTO/John Stillwell/WPA POOL (Photo credit should read JOHN STILLWELL/AFP/Getty Images) Getty Michelle Obama as the First Lady LONDON, ENGLAND - OCTOBER 11: A screen shows the First Lady of the United States Michelle Obama, as girls participate in a live conversation with her and other school girls around the world, via a video link at the Mulberry School for Girls n OCtober 11, 2016 in London, England. A Global Conversation on Girl's Education was a digital conversation with adolescent girls around the world. The event took place in celebration of International Day of the Girl. Girls in Washington, D.C., Jordan, Peru, Tanzania, and the Mulberry School for Girls in the United Kingdom spoke with one another about the challenges they have faced and potentially overcome in attaining an education. (Kirsty Wigglesworth-WPA Pool/Getty Images) Getty Michelle Obama as the First Lady Executive Director of Let's Move! and Senior Policy Advisor for Nutrition Policy at The White House Debra Eschmeyer (L) looks on as First Lady Michelle Obama (C) helps a child harvest sweet potatoes from the White House Kitchen Garden during a harvesting event at the White House in Washington, DC, October 6, 2016. / AFP / JIM WATSON (Photo credit should read JIM WATSON/AFP/Getty Images) Getty Michelle Obama as the First Lady WASHINGTON, DC - MAY 20: U.S. first lady Michelle Obama dances with students from turn around schools during a talent show at the East Room of the White House May 20, 2014 in Washington, DC. President Obamas Committee on the Arts and the Humanities held the first-ever White House Talent Show featuring performances by major artists and showcase the talents of students from schools participating in the Turnaround Arts program which helps to turn around low-performing schools and increase student achievement through arts education. (Photo by Alex Wong/Getty Images) Getty Michelle Obama as the First Lady WASHINGTON, DC - APRIL 06: First Lady Michelle Obama dances with members of the All Stars from from the television show "So You Can Dance" during the annual White House Easter Egg Roll on the South Lawn April 6, 2015 in Washington, DC. President Obama and the first lady hosted thousands of children for the annual White House event dating back to 1876 that features live music, sports courts, cooking stations, storytelling, as well as the Easter egg roll this year. (Photo by Mark Wilson/Getty Images) Getty

Senator Elizabeth Warren has also expressed her reservations, saying she was “troubled by” the speaking fee.

“I was troubled by that,” Warren said on SiriusXM's Alter Family Politics during an appearance to promote her new book.

“One of the things I talk about in the book is the influence of money. I describe it as a snake that slithers through Washington. And that it shows up in so many different ways here in Washington.”

Meghan McCain, a Fox News host, went a step further and called Mr Obama a “dirty capitalist” for agreeing to speak at the investment firm.

“The great irony is that Saint Obama, who is supposed to representing everything that is good and utopian on the left, is actually a dirty capitalist like the rest of us,” McCain, who is the daughter of Republican Senator John McCain, said.

While Mr Obama is said to have signed a contract for the event, the company is reported to be waiting to finalise arrangements with the Chicago native before making a formal announcement.

Eric Schultz, senior advisor to President Obama, defended the President in a statement sent earlier in the week and challenged the notion hefty speaking fees compromise the former President’s principles.

“As we announced months ago, President Obama will deliver speeches from time to time,” he told The Independent. “Some of those speeches will be paid, some will be unpaid, and regardless of venue or sponsor, President Obama will be true to his values, his vision, and his record.

“He recently accepted an invitation to speak at a health care conference in September, because, as a President who successfully passed health insurance reform, it’s an issue of great importance to him. With regard to this or any speech involving Wall Street sponsors, I’d just point out that in 2008, Barack Obama raised more money from Wall Street than any candidate in history – and still went on to successfully pass and implement the toughest reforms on Wall Street since FDR.

“And while he’ll continue to give speeches from time to time, he’ll spend most of his time writing his book and, as he said in Chicago this week, focusing his post-presidency work on training and elevating a new generation of political leaders in America.”