For the past several years now, Republican leaders have engaged in a ruthless and hypocritical campaign to define President Obama as foreign.

"I wish this president would learn how to be an American," said the Cuban-born John Sununu, who is of Palestinian and Greek descent.

"It appears that there has been deep penetration in the halls of our United States government by the Muslim Brotherhood,” said Rep. Michelle Bachmann, who only renounced her citizenship with Switzerland two months ago.

President Obama is the most "divisive figure in modern American history," declared Sen. Marco Rubio, who was born during the Nixon administration to Cuban parents.

"I don't think [President Obama] understands America," said Mitt Romney, whose father was born in Mexico.

The GOP leaders have challenged his birth certificate, his national origin, his patriotism, his religion, his staff, and his commitment to the country he represents as president.

But even as they attack Obama as un-American, these same Republicans seem blind to the irony of their own foreign attachments.

Watching Romney argue that Obama doesn't understand America comes with rich irony from a guy who moved $3 million of his own money to a mysterious Swiss bank account. And in order to avoid disclosure of what he was doing with his money overseas, Romney transferred ownership of a shell company in Bermuda to his wife the day before he was sworn in as governor of Massachusetts.

This is a guy who reportedly hid his money in offshore investments in the Cayman Islands and Luxembourg, and whose company represented investors who sheltered their money in Panama and the Bahamas. And when given a chance to run the U.S. Olympic Committee in 2002, Romney outsourced the U.S. Olympic team uniforms to Burma.

For all of Romney's ridiculous indignation that President Obama has turned America into a "European social welfare state," it was the French-speaking Mitt Romney who moved to Paris on a religious deferment during the Vietnam War.

And while Obama chose to bet on American auto workers in 2009, it was Romney who was willing to "let Detroit go bankrupt" and lose a million American jobs in the U.S. manufacturing industry.

If the party that considers itself the defenders of America's traditional family values wants to wage a war on who is more American, they should start by asking themselves why they take their marching orders from a twice-divorced Australian billionaire who owns Fox News and the Wall Street Journal.

And while Arizona Sheriff Joe Arpaio continues to challenge Obama's birth certificate, he shames the legacy of his parents who were both born in Italy. If Republicans are so concerned about a president's place of birth, they might want to explain why they weren't as concerned that John McCain was born in Panama or Romney's own father, who ran for president, was born in Mexico.

While they're at it, why did Republicans try to change the U.S. Constitution to allow Austrian-born Arnold Schwarzenegger to run for president?

For the past 30 years now, Republicans have labored arduously to redefine Americanism as conservatism. They've invented false rumors and trivial diversions about the pledge of allegiance, flag burning, the national anthem, and flag pins to measure one's patriotism. And yet they've failed to grasp how they've demeaned the rich legacy of America's true purpose as a beacon of light and hope for the rest of the world.

America's diversity is one of our greatest strengths. It has drawn millions of immigrants to our shores. No one knows that better than Obama, the son of a white American mother and a Black Kenyan father. As then Sen. Obama said in his 2004 keynote address at the Democratic National Convention, "I stand here knowing that my story is part of the larger American story, that I owe a debt to all of those who came before me, and that, in no other country on earth, is my story even possible."

All of us would do well to remember his words.

Keith Boykin is a New York Times best-selling author and former White House aide to President Clinton. He attended Harvard Law School with President Obama and currently serves as a TV political commentator. He will also be providing political commentary for BET.com each week.

The opinions expressed here do not necessarily reflect those of BET Networks.

BET Politics - Your source for the latest news, photos and videos illuminating key issues and personalities in African-American political life, plus commentary from some of our liveliest voices. Click here to subscribe to our newsletter.