Don’t mess with Moonbeam.

The most striking thing about San Francisco Gavin Newsom’s decision to withdraw from the race for California governor is that no one else is in the race. Newsom’s only opponent—Jerry Brown, the former governor and attorney general—may be the frontrunner in the polls, but he isn’t a declared candidate. Brown only recently set up an exploratory committee.

The 2010 gubernatorial election has been over for months. Newsom, by dropping out, simply spared himself any more wasted effort.

To put it another way: Some great competitors are said to be so intimidating that they win the game just by showing up. Jerry Brown managed to clear the field before he showed up—and more than seven months before the June primary.

The 2010 gubernatorial election has been over for months. (As I wrote in the American Prospect this summer, Jerry Brown is almost certainly California’s next governor. )

Newsom, by dropping out, simply spared himself any more wasted effort. Beating Brown, a popular former governor who is the son of one of the most fondly remembered governors of the past half-century, would be a difficult task even for the best-positioned politician. But beating Brown when you’re a mayor of San Francisco who has too little money and too much personal baggage (a well-publicized affair with the wife of a former top aide) may be simply impossible.

Much has been made of Newsom’s campaign problems: internal turmoil. The departure of a key aide. The difficulty of fundraising in the middle of a recession. The fact that Californians, like Americans, see San Francisco as largely out of the mainstream.

But in some sense, Newsom’s real opponent was history.

Recent polls showed Newsom losing to Brown even in the city he runs. But those polls weren’t all that surprising if you know the Brown story. Jerry is a San Francisco native. His grandfather had run a poker club in the Tenderloin. His father Pat, the former California governor, was a local politician whose first office was San Francisco district attorney.

Much has been made of Jerry’s own political rehabilitation—through his two terms as mayor of Oakland and current term as attorney general. But Jerry also has been helped by the resurgence in the reputation of his father.

During his two terms in the Capitol, from 1959 to 1967, Pat Brown was often criticized as weak and indecisive. (The phrase that stuck, “tower of Jell-O,” was aimed at him by a legislator). And he was rejected by California voters in 1966 in favor of an actor named Reagan.

But the job of California governor has defeated most of Pat Brown’s successors. With the passage of time, his record looks better. Today Pat Brown is remembered as a builder—of freeways and universities and waterworks. In an era of broken budgets and 12 percent unemployment, the California of Pat Brown has never seemed so far away, or so alluring.

Jerry Brown’s first governorship was in many ways a departure from that of his father, but he benefits from the nostalgia nonetheless. Recent political opponents who have conducted focus groups to test Jerry Brown’s vulnerabilities say they encounter the nostalgia every time. Even voters old enough to have voted against Jerry 30 years ago speak fondly of him now. His continued political existence, at age 71, reminds people of a time when they were younger and thinner, when the schools seemed better, when the traffic was lighter.

Jerry Brown has combined that appeal to nostalgia with political skills honed in five statewide campaigns and three presidential bids. For months, Brown dominated press coverage without putting on a campaign event. He outworked Newsom as a fundraiser, luring away some of the mayor’s biggest donors.

“He is a fierce competitor, very powerful in terms of how he conducts himself and runs his campaigns,” Rocky Delgadillo, who lost to Brown in the 2006 Democratic primary for attorney general, told me last summer. After he lost, Delgadillo said, Brown mentored him. “I learned a lot from him. He was open and available and has provided great advice to me.”

It’s easy to lose to such a man. And the three Republican candidates don’t look like much of a threat. The best-funded, former eBay chief Meg Whitman, appears to be the kind of amateur who the old pro could take apart quickly. The only question is how long she, or anyone else, can stay in the game.

Joe Mathews is a journalist, an Irvine senior fellow at the New America Foundation, and a contributing writer at the Los Angeles Times. He previously served as Justice Department reporter for The Wall Street Journal and as a city desk reporter at the Baltimore Sun. He is the author of The People's Machine: Arnold Schwarzenegger and the Rise of Blockbuster Democracy.