Rudy Giuliani told CNBC on Monday that high unemployment in places like Detroit is the result of the same Democratic policies that crippled New York City's economy before he became mayor in 1994.
"It's a tragedy, and it's a sell-out of those people to left-wing, socialist policies that don't work," he told "Squawk Box."
"The reason New York City was failing was not because people in New York are bad. The reason New York City was failing was because its policies were basically left-wing, socialist policies," he added.
The one-time GOP presidential candidate said he was able to turn around New York by using the same strategies Donald Trump wants to deploy nationally, including lowering taxes, reducing regulations and creating a business-friendly environment.
Trump plans to to further outline his economic and tax policies in a speech in Detroit on Monday, following a bruising week in which he publicly sparred with the Muslim family of a fallen U.S. soldier and initially refused to endorse leaders of the Republican Party in their re-election bids.
Giuliani said President Barack Obama had presided over the worst recovery since the Great Depression.
Annual U.S. economic growth has averaged 2.1 percent since the economy began growing again in 2009, according to the Center on Budget and Policy Priorities. The unemployment rate has fallen from 10 percent at its peak in 2009, the year Obama took office, to 4.9 percent last month.
Asked whether any event since the Great Depression had been equal to the 2008-2009 recession, Giuliani did not identify another downturn. However, he said John F. Kennedy tackled a recession by lowering taxes and Ronald Reagan beat back stagflation and helped drive an economic boom in the 1980s.
"Basically Donald Trump is following the model of John Kennedy and Ronald Reagan, and by the way, of Rudy Giuliani," he said. "Lower taxes. Put more money back into the hands of people. Let them spend it, rather than government bureaucrats who waste it."