Say it ain’t so! It seems as though every few years some Republican decides to unburden himself about the dirty tricks and sabotage he engaged in on behalf of a GOP candidate. Here’s the latest: It has been more than four decades, but Ben Barnes said he remembers it vividly. His longtime political mentor invited him on a mission to the Middle East. What Mr. Barnes said he did not realize until later was the real purpose of the mission: to sabotage the re-election campaign of the president of the United States. It was 1980 and Jimmy Carter was in the White House, bedeviled by a hostage crisis in Iran that had paralyzed his presidency and hampered his effort to win a second term. Mr. Carter’s best chance for victory was to free the 52 Americans held captive before Election Day. That was something that Mr. Barnes said his mentor was determined to prevent. His mentor was John B. Connally Jr., a titan of American politics and former Texas governor who had served three presidents and just lost his own bid for the White House. A former Democrat, Mr. Connally had sought the Republican nomination in 1980 only to be swamped by former Gov. Ronald Reagan of California. Now Mr. Connally resolved to help Mr. Reagan beat Mr. Carter and in the process, Mr. Barnes said, make his own case for becoming secretary of state or defense in a new administration. What happened next Mr. Barnes has largely kept secret for nearly 43…