Donald Trump says the U.S. economy is rigged.

If that line sounds familiar, it should. Bernie Sanders uses it constantly in his campaign. Sanders even devotes a section of his website to explaining the rigged economy.

As Trump bashed rival Hillary Clinton in a speech Wednesday for being a "world-class liar," he also sought to win over Sanders' supporters and the working class.

"It's not just the political system that's rigged, it's the whole economy," Trump said, to much applause.

The middle class can't get ahead, Trump argued, because the system is controlled by big donors, big businesses and big bureaucrats who all want to keep wages down while enriching themselves. Trump vows he's the only one who can overhaul the system.

"Hillary Clinton's message is old and tired. Her message is that things can't change. My message is that things have to change," Trump said. "We're asking Bernie Sanders supporters to join our movement."

Related: The next president will likely face a recession

The U.S. economy has problems

Few economists would go as far as Trump and Sanders (and Democratic Senator Elizabeth Warren) in saying the entire system is "rigged," but it's hard to deny some key facts about the U.S. economy:

-America's middle class is shrinking

-A typical family is earning the same today as in 1996

-The majority of Americans believe their children will be worse off than them financially

-Men, especially white men, have fallen out of the job market

Mere hours before Trump delivered his speech, the International Monetary Fund put out a highly critical assessment of the U.S. economy. A key red flag, the IMF said, the high rate of poverty and inequality in the world's No. 1 economy.

"The latest data shows almost 15% of Americans -- or 46.7 million people -- living in poverty," IMF director Christine Lagarde said, warning that unless that changes, it will "corrode the underpinnings of growth...and hold back gains in U.S. living standards."

Related: How I went from middle class to homeless

Trump's plan to fix the system

There's a lot of pessimism about the economy. Even many Americans who have jobs tell CNNMoney they feel one step away from financial ruin because they can't save enough to give them a safety net or extra money to invest for the future.

The question is what will Trump do to change the situation?

In his speech Wednesday, Trump reiterated that he will get tough on trade, restrict immigration, repeal Obamacare, scale back regulations and pass massive tax reform to lower taxes for individuals and corporations.

But economists and business leaders across the political spectrum have blasted Trump for some of these ideas, especially his plans to put walls -- literally and figuratively -- up on trade and immigration.

Related: Trump's plans would cost 3.5 million jobs

Numerous experts have said if Trump's plans were enacted, they would send the U.S. into a recession. Early this week, Moody's Analytics predicted Trump's policies would cause unemployment to jump and the U.S. to lose about 3.5 million jobs.

There are also concerns that Trump's tax plan would leave the U.S. far deeper in debt and actually give many breaks to the top 1%.

Trump dismisses the criticism. When pushed about how his plans to slap large tariffs on goods imported from China or Mexico would make shopping trips a lot more expensive for working class Americans, Trump is fond of saying that everything is negotiable.

If he becomes president, Trump promises, "parents are going to start dreaming big for their children again."