Bush’s defiant simplicity has become the vivid hallmark of his suddenly not-so-new presidency. He’s taken stark, stubborn–and, critics would say, simplistic–positions on issues ranging from Alaska drilling to taxes to nuclear deterrence. On a personal level, Bush likes nothing more than to spend a quiet weekend at Camp David, or, even better, weeks on end at his ranch in Crawford, Texas.

The president said it best in, of all places, Rome, while touring the Forum recently, surrounded by reporters who peppered him with questions on a host of topics. His bottom line: “I know what I believe, and I believe that what I believe is right.”

Hardly Cicero, but it was the essence of George Bush the Younger.

The PB&J president provokes a range of reactions: laughter, derision, concern. It makes me curious. He’s no dummy, but his poll numbers are dropping, so why operate this way as president? Is this who he is, or is there a more complicated reality? Why would a leader seen by many–not all of them Democrats–as not ready for prime time risk looking … simple.

The answer is, well, complicated. Bush’s approach to politics is rooted in–and limited by–his father’s experiences; his own rise–and the resentments that come with it–in his brief political career in Texas; and in a strategy of legislative poker he developed in Austin.

Here’s my bottom line: Bush may seem as plain as PB&J, but he’s a player with a plan. The question, of course, is whether it’s a winning one.

Here’s my list of the whys and wherefores–and the potential pitfalls–of Bush’s PB&J approach to the presidency:

LISTEN TO KENNY ROGERS: Having followed Bush’s career as the governor of Texas, I think he’s planning to cut any number of deals, but only at what he regards as the very last possible moment. You can almost hear him hum the lyrics of the country hit, “The Gambler”: “You gotta know when to hold ’em, know when to fold ’em … "

In dealing with the Texas Legislature, Bush played dumb and kept movin’, sticking with proposals–such as a sweeping education-tax reform–until there was no chance the thing would pass as he’d designed it. Then he accepted whatever the legislature would give him, and called it a victory. He did veto a state patients bill of rights, but let a second version go into law without his signature.

I think he thinks that unless he takes the hardest and purest possible line for as long as he can, he won’t get anything out of the jumbled mess that passes for a “legislative process” on Capitol Hill. His experience with the tax bill proved his theory correct, or so he believes. His stubborn insistence on pushing that plan led–with backing from the House GOP leadership–to the passage of the biggest tax cut in 20 years.

I would look for Bush to ultimately accept just about whatever Congress will give him on the patients bill of rights, energy, his faith-based initiative and education reform. He’ll stick to his guns until he knows it’s time to put them back in the holster.

I expect him to behave the same way on the question of stem-cell research. He and his handlers are stressing how pained the decision is, how he is weighing evidence, thinking of the moral issues, praying on the advice he got from the pope in Rome. He’ll take a deal.

STICK WITH TEXAS TRADITIONS: Bush glories in his Texasness, and why not? Despite his Mayflower ancestors and mega-prep education, he’s the real deal. But while he may have learned the poker theory of politics in Austin, there are limits to the value of what he learned there–and he is running headlong into them these days.

Bush thinks that he can ignore all but the leadership of the legislature–i.e., the Congress–because that’s what he did in Austin. He thinks that Republicans will fall in line because that’s what they did in Austin, and that most Democrats are “moderates,” amenable to good ol’ boy deals, because that’s what they had in Austin.

In Texas, they don’t have tree-hugging, socially tolerant Republicans like upstate New Yorkers Sherwood “Sherry” Boehlert or Amo Houghton–two able noblemen straight out of a James Fenimore Cooper novel. In Texas, they don’t have (since LBJ died) Democratic leaders like Tom Daschle and Dick Gephardt, two dedicated liberals with hides and minds as tough as beef jerky. In Texas, they don’t have members of the legislature who are so suspicious of the Oil Bidness, either.

The risk for Bush: The Dems will outthink and outlast him, forcing him either to veto measures–such as a patients bill of rights–or accept deals the GOP right wing loathes.

STAY RIGHT WITH THE RIGHT: This, of course, has been the cardinal principle of Bush’s political career since he launched his first gubernatorial campaign in 1993. He still believes in theory. For the most part, his appointments and decisions on abortion issues have been down-the-line pro-life; he hasn’t wavered in his commitment to a pro-exploration theory of energy policy; he’s down-the-line on a mobile missile shield; his starting assumption about international agreements is skepticism.

The big test is at hand: Bush’s decision on stem-cell research. I don’t think it’s likely that he’ll adhere to the Vatican’s absolutist position. Even most Catholics think that, under controlled circumstances, research should not only be permitted but supported by federal money. But Bush was intent on showing his respect for, and concern for, the pope’s views. Some critics viewed his audience with the pope as a mistake–subjecting him to a public lecture from His Holiness on the topic.

I think it served Bush’s purpose, which was to show that the president of the United States is a pained man of principle, and is only changing his campaign position because of overwhelming scientific evidence–and possibilities–he did not understand when he took his first public stand, in 1999, opposing federal funding for such research.

BE ‘UMBLE: As everyone knows, Bush’s background is hardly PB&J. But every president needs a log cabin myth. His dad didn’t have one, but he did have a sterling war record as a brave Navy pilot.

Bush the Younger is a simpler guy, and has striven to be that way. His log cabin is a history of too much drink. Since he went cold turkey in 1986, he’s simplified his life and tastes, but he was never a caviar-and-filet mignon-type of guy. He once told me that if he didn’t win the White House he would be happy to leave politics and take up fishing on a lake. I think he meant it.

So the PB&J was a symbol of the life he has chosen.

One other thing. Bush is rather a skinflint, and the lunch he chose at the Capitol the other day was the cheapest thing on the menu.