In A. Alvarez' book, POKER: BETS, BLUFFS, AND BAD BEATS, the poker habits of presidents are discussed. Truman often played with the White House press corps, most famously on board the cruiser Augusta, while he was deciding whether or not to drop the atom bomb on Hiroshima. Eisenhower was a regular winner while in the service, but gave up the game while he was still in the army because he did not enjoy seeing fellow officers losing more than they could afford. Nixon was a tough player who financed his first campaign for Congress with poker winnings. He later gave up the game when he became Eisenhower's vice president, but he still had one big bluff to run through:

From David Spanier's book, TOTAL POKER:

The basis of the Watergate coverup was that if the full weight and prestige of the Presidency were committed to the cover-up, Congress would not "see" . . . The bluff itself was not entirely misconceived; after all, the White House had the immense advantage of running the game, so to speak, and of exercising its control over the principal players. The bluff failed in the end because the hands were recorded in the form of tapes. That was why the cover-up was ultimately exposed. If the tapes had been destroyed instead of being doctored, the probability is that Congress would not have nerved itself to bring in a Bill of Impeachment, and Richard Nixon's greatest bluff would have "held."

From A. Alvarez:

This is a shrewd analysis, but wrong, I think, in one detail: Congress only got into the game late, when the bluff was already out of hand. At the start Nixon's opponents were merely a couple of hack reporters from the Washington Post who would, he though, easily be intimidated. It was as though, in a game of five-card stud, Nixon was showing ace, king, queen, and jack of spades but had a worthless card of a different suit in the hole. He bet $1,000,000, and the Washington Post called him with nothing better than a pair of wired deuces. In other words, Nixon bet the presidency and was seen. It was an insane call, but then journalists are notoriously poor poker players. Maybe Nixon would have known this if he had played with them as often as President Truman did. But he loathed the press as much as they loathed him, and he overrated their poker skills. The Watergate cover-up is the prime example of the old poker maxim "Never try to bluff a mug."