Ross Perot on May 5, 1992 in New York City. (AP Photo)

Texas billionaire Ross Perot has endorsed Mitt Romney for president, saying the future of the country is at risk. 

"At stake is nothing less than our position in the world, our standard of living at home, and our constitutional freedoms," Perot wrote in a statement. "Mitt has the background, experience, intelligence, and integrity to turn things around."

Running for president in 1992 and 1996, Perot was the most successful third-party candidate in nearly a century. Despite dropping out of the 1992 race for months, he took nearly 19 percent of the popular vote; exit polls suggest he pulled support equally from President George H.W. Bush and challenger Bill Clinton. 

Forbes lists Perot's wealth at $3.5 billion. He made his fortune in computer systems and is now invested in real estate and oil. 

His 1992 campaign was largely focused on the federal deficit. After getting back in the race five weeks before Election Day, he proposed a plan that combined tax increases, spending cuts and business incentives. 

Only a couple of weeks ago, Perot told CSPAN that neither party was taking deficit reduction seriously. "Nobody that's running really talks about it, about what we have to do and why we have to do it," he said. "They would prefer not to have it discussed."