Donald Trump’s election victory was blindsiding. For many, it was a moment that forced them to pause and then double back.

A number of key political figures have climbed down from their scathingly critical positions and extended conciliatory messages pledging to work with the incoming President.

Barack Obama said everyone in the White House is “rooting for his success” while Speaker of the House Paul Ryan claimed Mr Trump’s win “marks a repudiation of the status quo of failed liberal progressive policies”.

But one man is unafraid to challenge him: the man who ran for the Democratic nomination with antithetical policies to Mr Trump’s, Bernie Sanders. The socialist senator and former mayor, 74, released a careful statement responding to Mr Trump’s new position as President-elect.

He also demonstrated an understanding of why Mr Trump’s presidency attracted such support.

President Trump protests Show all 20 1 /20 President Trump protests President Trump protests Patrons hold a sign as people march by while protesting the election of Republican Donald Trump as the president of the United States in downtown Los Angeles, California Reuters President Trump protests Demonstrators rally following the election of Republican Donald Trump as President of the United States, in Oakland, California Reuters President Trump protests Demonstrators march following the election of Donald Trump as President of the United States Reuters President Trump protests Thousands of protesters rallied across the United States expressing shock and anger over Donald Trump's election, vowing to oppose divisive views they say helped the Republican billionaire win the presidency AFP/Getty Images President Trump protests Demonstrators protest outside the Chicago Theatre in Chicago, Illinois Getty President Trump protests A police officer aims a launcher after demonstrators threw projectiles toward a line of officers during a demonstration in Oakland, California Reuters President Trump protests An officer examines a vandalized police vehicle as demonstrators riot in Oakland, California Reuters President Trump protests Demonstrators take over the Hollywood 101 Freeway just north of Los Angeles City Hall in protest against the election of Republican Donald Trump as President of the United States Reuters President Trump protests A woman holds up a sign reading 'Trump you are an Idiot' as demonstrators gather during a protest against President-elect Donald Trump outside the City Hall building in Los Angeles, California EPA President Trump protests A masked demonstrator gestures toward a police line during a demonstration in Oakland, California Reuters President Trump protests Demonstrators protest against the election of Republican Donald Trump as President of the United States, near the Trump International Hotel & Tower in Las Vegas, Nevada Reuters President Trump protests Musician Lagy Gaga stages a protest against Republican presidential nominee Donald Trump on a sanitation truck outside Trump Tower in New York City Getty President Trump protests A woman yells as she takes part in a protest against President-elect Donald Trump in Seattle's Capitol Hill neighborhood AP President Trump protests A man dressed in red-white-and-blue sits on the curb during a protest against President-elect Donald Trump in Seattle's Capitol Hill neighborhood AP President Trump protests A protester sets off fireworks during a protest against President-elect Donald Trumpin Seattle's Capitol Hill neighborhood AP President Trump protests University of California, Davis students protest on campus in Davis, California, U.S. following the election of Donald Trump as President of the United States Reuters President Trump protests An Oakland police officer checks out damage after a window was broken by protesters at a car dealership in downtown Oakland, Calif AP President Trump protests A protester faces a police line in downtown Oakland, Calif AP President Trump protests President-elect Donald Trumpís victory set off multiple protests AP President Trump protests A fire burns during protests in Oakland, Calif AP

“Donald Trump tapped into the anger of a declining middle class that is sick and tired of establishment economics, establishment politics and the establishment media. People are tired of working longer hours for lower wages, of seeing decent paying jobs go to China and other low-wage countries, of billionaires not paying any federal income taxes and of not being able to afford a college education for their kids - all while the very rich become much richer.

“ To the degree that Mr. Trump is serious about pursuing policies that improve the lives of working families in this country, I and other progressives are prepared to work with him."

But his message added an important caveat.

“To the degree that he pursues racist, sexist, xenophobic and anti-environment policies, we will vigorously oppose him.”

Mr Sanders’ statement will only bolster growing calls for him to run in the 2020 election. His policies had a clear focus on closing the stark gap between the wealthy and those living in poverty across the US, creating access to free health care and education, creating a living wage, tackling racial inequality and introducing a “fair and humane” immigration policy.

In contrast, Mr Trump has confirmed plans to repeal Obamacare, potentially leaving 22 million Americans without healthcare insurance, and begin the deportation of undocumented immigrants living in the US.