MIchael Bloomberg, the independent mayor of New York City, is no one’s idea of a hardline Republican conservative. Media titan Rupert Murdoch, whose empire includes Fox News and The Wall Street Journal, is no one’s idea of a squishy Republican moderate. And Boston Mayor Thomas Menino, a lifelong Democrat, is no one’s idea of a Republican at all.

It isn’t every day that three men with such disparate ideological profiles find common cause, let alone on a high-profile issue that has been roiling American politics for years. But there they were at Boston’s Seaport Hotel one evening last week, jointly making a nonpartisan case that reforming the nation’s dysfunctional immigration system is essential for economic revival. Without the growth fueled by immigrants – especially foreign-born entrepreneurs – the United States is unlikely to retain its preeminent position in the world. In Bloomberg’s vivid phrase, America is “committing economic suicide” by making it too hard for ambitious foreigners to enter the US and unleash their drive and ingenuity.

Opening the Boston forum, Menino was effusive in his praise for Bloomberg, whose social liberalism, especially on gun control, complements his. “I am proud to call him my friend,” Menino said.

But the mayor was at loss for something nice to say about Murdoch, the former owner of the conservative Boston Herald. The best he could manage was to thank him “for being here and sharing his views.” He started to make a dig about “those headlines, Rupert” – then apparently thought better of it, and merely observed wryly that the News Corp. chairman ensures “a diversity of opinion.”

What was striking about the discussion that followed, however, was its unity of opinion, above all on the subject of immigrants and their economic impact.

Menino ran through some local numbers. There are 8,800 immigrant-owned small business in Boston, he said, producing nearly $3.7 billion in annual sales and employing more than 18,000 people. New Americans have swelled Boston’s population to 625,000, its healthiest level since 1970 – healthy because “more people mean more talent, more ideas, and more innovation.” They also mean more revenue: Boston’s immigrants spend $4 billion per year, generating $1.3 billion in state and federal taxes. For generations immigrants have rejuvenated Boston, said the mayor. “They make this old city new again and again.”

He got no argument on that score from Murdoch, an Australian native who became a US citizen in 1985. “An immigrant is more likely to start a small business than a non-immigrant,” said Murdoch, whose career exemplifies the phenomenon. “You go to Silicon Valley, and you realize it’s misnamed: It’s not the silicon” that makes it such a high-tech dynamo. “It’s the immigrants.” Ambitious foreigners “want to dream the American dream,” and it’s in America’s national interest to help them do so.

There is an abundance of empirical evidence that immigration is a tremendous economic driver. A study by the Partnership for a New American Economy, a coalition of mayors and business leaders advocating for more rational immigration laws, is awash with eye-opening data on immigrant entrepreneurship. More than 40 percent of Fortune 500 companies were founded by immigrants or their children, and immigrants are now more than twice as likely as US natives to start a business. Though the foreign-born account for less than 13 percent of the US population, they created 28 percent of all new American businesses in 2011.

Murdoch and Bloomberg, two of the partnership’s co-chairmen, argue that if only more Americans understood what remarkable job-creators immigrants tend to be, fewer politicians would feel the need to play to anti-immigrant xenophobia. Fewer voters would believe the popular canard that foreigners enter America to live off welfare – or the equally popular, if contradictory, canard that immigrants steal jobs that would otherwise go to Americans.

“People don’t come here to put their feet up and collect welfare,” Bloomberg said. They come here to work. If there are no jobs, they don’t come.“ You’d never know it from the clamor over illegal immigration – "Put a damn fence on the border … and start shooting,” one GOP congressional candidate recently advised – but illegal border crossings have sharply declined.

What hasn’t declined is the hunger of strivers and dreamers the world over – talented entrepreneurs eager to bring their gifts here and make a success of themselves. Those would-be immigrants are an extraordinary growth hormone we can’t afford to spurn. A broken immigration system threatens America’s future economic vitality. Fixing that system must become a priority – for left, right, and center alike.

(Jeff Jacoby is a columnist for The Boston Globe. His website is www.JeffJacoby.com).