But Republican support for the president remained strong and the idea of impeachment remained far-fetched. Even after Dean testified, Nixon remained confident that he could survive. As John Farrell writes in his award-winning biography of the president, the testimony until that point was “hearsay.” At one point, Dean had suggested that conversations were recorded, but he had no evidence to prove that that was the case. As a result, Dean’s allegations were his word against the claims of President Nixon. One Republican pollster told White House officials, “Barring some new sensational revelations, it would appear that the tempest … has passed its peak.” Administration officials believed that they would be able to discredit people like Dean as opportunistic and self-serving. “Why on earth should I believe anything that John Dean says?” the television personality Dick Cavett asked his viewers. Polls showed that only about 50 percent of those surveyed believed Dean.
But in mid-July, everything changed. Senate Watergate staffers found evidence through interviews that the White House did indeed tape conversations. The committee lawyers Scott Armstrong and Don Sanders confirmed the discovery during their secret pre-testimony interview on Friday, July 13, with Butterfield, whom they dragged into their offices. Sitting in a messy Senate room, the lawyers handed Butterfield a transcript that one of Nixon’s lawyers had turned over to the Republican staff. Looking at the document, Butterfield understood immediately that they knew this was the transcript of a conversation that had been taped. “I thought to myself that this had to come from the tapes—the very thing I’m worrying so much about. So, I just hemmed and hawed,” Butterfield later remembered. Sanders then asked Butterfield directly if there were any listening devices in the Oval Office. Butterfield did not feel comfortable lying to them and feared ending up in jail. “I’m sorry you asked that question,” he told them. “Yes, there was, and that’s where this document had to come from.” When Butterfield admitted to lawyers the existence of the recordings, he recalled, “they were ecstatic.” Sanders tracked down the committee member Frank Thompson, a Republican, who was having a drink at the old Carroll Arms Hotel, and told him the news.
Presidents since Franklin D. Roosevelt had been recording White House conversations. Although Nixon had initially taken down Lyndon B. Johnson’s recording system, in 1970 he replaced it with a noise-activated system that recorded everything, instead of the manually operated system used by his Texas predecessor. Only a small number of people, including Butterfield, knew of the existence of the tapes.
By this time, much of the country was tuned into the hearings. Even popular soap operas reported a steep decline in their ratings, as viewers switched to the real-life drama in Washington, D.C. In a dramatic testimony on Monday, July 16, with television cameras covering the proceedings, Butterfield, who was a surprise witness, revealed to the nation that the president had recording devices in the White House that automatically taped conversations. When Thompson, to the consternation of some Democrats who wanted more credit, asked, “Are you aware of the installation of any listening devices in the Oval Office of the president?” Butterfield responded: “I was aware of listening devices, yes, sir.” Butterfield went onto explain that the president had been taping the conversations “for posterity.” He had been in charge of having machines installed that automatically recorded the Oval Office telephone and conversations in numerous rooms.