It has happened already: Muttgate. Sen. John McCain has a dog; Sen. Barack Obama does not. The Associated Press and Yahoo found that pet owners favor McCain over Obama, with dog owners particularly in McCain's corner. Even cat owners went for McCain.

One pet owner said dog owning "tells you that they're responsible at least for something, for the care of something."

Presidential dogs have not only been prominent in politics, in more than a few instances they've been image breakers and makers.

When Buddy, Bill Clinton's Lab was killed by a car in 2000, the nation mourned. The national empathy for that loss could have played a small part in easing leftover tension from White House scandals at the time.

Vice-presidential candidate Richard Nixon, hounded (couldn't resist) by allegations that rich backers were supporting his luxurious lifestyle, made "the Checkers speech" in which he emotionally defended accepting the gift of a cocker spaniel. "Regardless of what they say about it, we're gonna keep it," Nixon declared. And Nixon remained on the ticket.

Less fortunate was Lyndon Johnson, who scandalized dog owners by picking up one of his two beagles by the ears. Presidents by that time knew the value of being considered dog lovers and Johnson was a consummate politician, but he stumbled badly with the ear-pulling incident. "Those Republicans are really bashing me about picking those darned dogs up by the ears," he grumbled to his vice president, Hubert Humphrey. There were possibly other issues involved in Johnson's decision not to run for a second term, but Beaglegate certainly wouldn't have helped.

Harry Truman, who defended Johnson, is rumored to have said, "If you want a friend in Washington, get a dog." He didn't have a dog and perhaps should have listened to his own advice. In office Truman managed to score among the lowest public opinion polls of any president.

President Bush has had two Scotties (Barney and Miss Beasley), and the late Spot, a springer spaniel and son of Millie, the White House dog when the first George Bush was president. However, we hardly hear any news about them any more. They might not have been able to boost the president's image miraculously, but they might, at least, help.

Theodore Roosevelt had a virtual zoo in the White House. His six kids had ponies, lizards, rats, squirrels, and even bears and a garter snake named Emily Spinach. Teddy also had a bull terrier, Pete, who was banished from the White House after he ripped the britches of the French ambassador. Given Teddy's pugnacious image, it's hard to imagine his dog doing anything else.

Caroline Kennedy's dog, Pushinka, was a gift from Nikita Khrushchev and though no doubt had a most thorough exam to make sure the dog was not implanted with listening devices, may have also represented a bridge to the Soviet Union.

For their part, the Reagans accepted Lucky, a large sheepdog, as a gift from a March of Dimes poster child. Though Lucky surely helped promote that cause, he didn't do so well in the White House. He used to drag Nancy Reagan around and also misbehaved on the White House carpets.

From George Washington's hounds to Calvin Coolidge's dog, Rob Roy, from Franklin Roosevelt's famous black Scottie named Fala to Gerald Ford's golden retriever named Liberty, presidential dogs have played an important part in the images of their owners.

Obama, perhaps picking up on this, has supposedly promised his daughters a dog when the campaign is over. The American Kennel Club has even gotten involved, helping decide what breed it should be. The AKC has narrowed the search down to bichon frisi, miniature schnauzer, poodle, or soft-coated wheaten terrier — a breed so obscure that it could not possibly create controversy.

Regardless of the publicity value of a presidential dog, there is one bottom line positive benefit in having a Fala, Spot, Buddy, Lucky or whoever — when times get tough, when the economy goes sour, when international tensions are at a peak, a sympathetic, sloppy ear lick can do a world of good.

Joel M. Vance is a writer based in Missouri.