NEW YORK -- The Grand Old Party is no longer the party of business, Michael Bloomberg said Tuesday.

“The Republican Party is becoming the party of labor,” this city's former mayor said in a keynote speech at the Bloomberg Philanthropies What Works Cities Summit at Manhattan’s ritzy Lotte New York Palace. “The Republican Party does not represent business anymore.”

Bloomberg seemed to be referring to the surprise move in October by the International Brotherhood of Teamsters, one of the largest labor unions in the United States, to seek a meeting with Republican presidential hopeful Donald Trump.

Unions have traditionally backed Democratic candidates, and frontrunner Hillary Clinton appears to be leading with labor against insurgent candidate Bernie Sanders. Black workers had the highest rate of union membership last year, according to data from the Bureau of Labor Statistics. Meanwhile, bombastic reality star Trump's populist views and racist, xenophobic rhetoric have resonated strongest among poor, white male voters.

Nevertheless, days after the Teamsters' announcement, Chris Shelton, president of the 600,000-member Communication Workers of America, told Politico that his union would endorse Trump “if our members come out with Donald Trump.”

During a speech in New Hampshire in February, Trump said: "I have tremendous support within unions, and I have tremendous support in areas where they don't have unions. ... The workers love me."

To the distress of some of his party’s establishment, Trump has aimed some of his vitriol at Wall Street, corporations and the wealthy. He has argued for higher taxes on hedge funds and claimed that "hedge fund guys are getting away with murder." He has called for boycotts against Apple, Starbucks, Macy’s and Oreo maker Nabisco. He has vowed to create “problems” for Amazon if its billionaire CEO Jeff Bezos were to use his political influence to disrupt Trump’s hope of clinching the nomination.

Despite touting his dubious business bona fides as a central part of his platform, Trump appeals to a strain of anger at economic inequality and the perception that the system is rigged against the poor -- the same strain that has turned self-described "democratic socialist" Bernie Sanders into a serious contender against Hillary Clinton, Bloomberg said.

The rift between big business and the party that has long claimed to represent its interests has been exacerbated over the last year as Republican lawmakers and candidates refused to acknowledge humans’ role in changing the climate and backed discriminatory laws against LGBT people.

Last year, while the country awaited the Supreme Court decision that ultimately lead to the legalization of same-sex marriages nationwide, nearly 400 companies urged the court to rule in favor of marriage equality. Now, legions of corporate titans are battling Republican lawmakers throughout the South and Midwest over legislation aimed at preventing transgender people from using bathrooms that correspond with their gender identity and allowing businesses to discriminate based on gender identity or sexuality.

“The Republican Party is becoming the party of labor. It does not represent business anymore.” former NYC Mayor Michael Bloomberg

The divide between the GOP and corporate America may be even bigger on climate change. The two leading Republican candidates -- Trump and Texas Sen. Ted Cruz -- deny climate change as a hoax. John Kasich, the Republican hopeful in third place, isn’t much better.

Yet climate change, largely caused by big industry, has become the foremost economic risk of this year, the World Economic Forum said in January.

“Climate change is exacerbating more risks than ever before in terms of water crises, food shortages, constrained economic growth, weaker societal cohesion and increased security risks,” Cecilia Reyes, the chief risk officer of Zurich Insurance Group, said in a statement at the time.

By contrast, clean energy represents a multi-trillion dollar opportunity, Secretary of State John Kerry said earlier this month.

President Barack Obama said in December that the “American Republican party is the only major party that I can think of in the advanced world that effectively denies climate change.” That same month, broad coalitions of major corporations backed the historic 196-country climate treaty signed last year in Paris. The accord aims at keeping the world from warming beyond 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial temperatures.

Climate change has already begun to cause more violent, unpredictable storms, drought and flooding. Unless global warming is curbed, much of human civilization could become unsustainable by the end of the century.

Bloomberg seems bent on addressing that problem, too. Beyond his philanthropic work -- pushing mayors of cities around the country to use data to improve policy decisions -- he owns Bloomberg New Energy Finance, a data and consulting firm fixated on the renewable energy industry. The organization has its work cut out for it: The world needs to spend roughly $7 trillion over the next decade to combat climate change.

The 74-year-old Bloomberg, who returned as chief executive of his eponymous financial data and media firm in 2014, said he originally registered as a Democrat in his hometown of Boston and later in New York, where he has lived since the 1960s. He became a Republican in 2001 to run for mayor, in large part because his pro-business views seemed out of place in New York’s Democratic Party at the time. He left the Republican Party in 2007 and registered as an independent, insisting that “real results are more important than partisan battles and that good ideas should take precedence over rigid adherence to any particular political ideology.”

The larger point there may be that letting partisanship and demagoguery trump fact is simply bad for business.

“I’m not trying to knock Donald Trump," Bloomberg said, "but I do think what you’re seeing in this election, in some cases you argue on the facts, in some cases it becomes a religion -- the facts don’t matter at all.”