Earlier this week, Mitt Romney spoke approvingly of a supporter’s plan to amend the Constitution “to say that the president has to spend at least three years working in business before he could become president of the United States.”

Romney’s requirement would have prevented most of America’s greatest presidents — such as Abraham Lincoln, Teddy Roosevelt, and Franklin Roosevelt — from taking office. Some of America’s worst presidents would have met the standard, however.

Here are six presidents whose extensive business experience didn’t translate well to the Oval Office:

Andrew Johnson

Born into poverty, Johnson achieved wealth by founding and running a successful tailoring business. He went on to become one of America’s worst presidents, and the first to be impeached.

Warren G. Harding

Harding was a hugely influential newspaper publisher before becoming President, where his legendary corruption left him ranked by many historians as the worst president in history.

Herbert Hoover

Hoover’s successful mining business made him one of the richest men to ever serve as President. His business experience didn’t help him respond to the great depression, however, and Hoover is widely considered to be among worst presidents ever.

Jimmy Carter

Carter ran a successful peanut farming business before becoming president, where he was unpopular and lost his re-election campaign to Ronald Reagan in a historically large landslide.
George H.W. Bush

Bush became a millionaire running Zapata Petroleum Company before embarking on a long political career that eventually put him in the White House. With his approval rating dipping as low as 29 percent, he was easily defeated in his re-election bid by Bill Clinton.
George W. Bush

After leading a number of failed oil companies, Bush eventually found success as owner of the Texas Rangers baseball club. Despite this business experience — and being the first president with an M.B.A. — Bush finished his White House tenure with the worst job creation record in modern history.