John McCain is a lucky guy. Divine intervention, in the shape of Hurricane Gustav, gave him the perfect excuse to cancel a valedictory by President Bush and a chiding address by Vice President Cheney due to be delivered yesterday. With Barack Obama out to convince voters a McCain presidency would be little more than a Bush third term, the giant wind came right on cue.

But Mr. McCain can also make his own luck. The Democratic love-in at Invesco Field in Denver may be a chilling reminder to students of history that sports stadiums filled with chanting converts are not always the best guide to whether a charismatic leader is worth the fuss, but it was certainly what is called “good television.” Then Mr. McCain let off his secret weapon: Sarah Palin.

The surprise choice of a woman vice presidential candidate rained on Mr. Obama’s finest hour, raised the ghost of Hillary Clinton in the newly “united” Democratic Party, signaled that McCain Republicans are different from their predecessors, and flattened Mr. Obama’s bounce in the polls.

On the face of it, Mrs. Palin inspires the parts of America Mr. Obama finds hard to reach: the blue collar clad, religion clinging, skirt wearing, gun toting, moose hunting, church going majority. But there is still a lot to learn about the private life of the Palins, and for Mr. McCain’s sake Mrs. Palin’s life must be laudable in every particular.

It was a typical McCain gamble. But four days later, one must ask how smart was it to pick a woman he had met only once and then only briefly? The answer came surprisingly quickly: Yesterday, we learned Mrs. Palin’s 17-year-old daughter, Bristol, is five months pregnant, although she is not married. So much for Mr. McCain’s due diligence.

This will not trouble progressives, who have long thought marriage outdated. But it may give conservatives pause. Voters will come to judge whether the morality Mrs. Palin imbued in her children was adequate or whether she put work before providing the best possible pastoral care.

On the upside for Mr. McCain, Mrs. Palin is a competent mayor and governor who has gone after corruption in her own party. She is a Christian, a lapsed Catholic, which may reassure those who doubt his late conversion to the merits of the Christian conservative movement.

Mrs. Palin, a member of the Wasilla Assembly of God until 2002, is against abortions in any circumstances, which many women will find hard to stomach. She believes creationism should be taught alongside science in Alaska’s schools, another view sure to raise alarm.

Mrs. Palin is hardly a conventional wife and mother. She chose not to stay at home and tend to her husband and her four, now five, children, as many conservatives expect of women. She was too busy riding her hectic career, becoming the first woman and the youngest ever governor of Alaska.

Voters will want to know how Mrs. Palin managed a full time career while tending properly to her large family. She became pregnant at age 43, which is a surprising choice for a woman who juggles bringing up five children with running a sprawling state of 680,000 citizens that is vaster than Britain, France, and Germany combined. Did she intend to become pregnant so late in life? If not, what does that say for her judgment and her competence?

For a working woman to bring up one child is a triumph of organization, so how does she find the time and energy to tend to five? In progressive households, men sometimes become house husbands. But Mr. Palin is off at the North Slope oil fields for long periods. If Mrs. Palin employs child caregivers, who are they and how qualified are they? Does she pay minimum wage, or more? Does she pay the appropriate tax and social security contributions?

The impending birth of Mrs. Palin’s first grandchild will be sure to attract attention, though it will arrive after the election. But baby Trig will also attract close scrutiny. Some may find this intrusive.

However, when choosing a person who might inherit the most powerful office in the world if the 72-year-old Mr. McCain’s heart were to fail in the next eight years, nothing should be off limits. Mrs. Palin said there was never any doubt she would go full term with Trig, even though tests showed the boy would have Down syndrome.

Trig is undoubtedly a well loved child. But did the Palins make the right decision? If Mrs. Palin became president, would she expect all American women to follow her example? Would she attempt to overturn Roe v. Wade?

The Democrats have a difficult task. They must draw advantage from the consequences of Mrs. Palin’s uncompromising lifestyle without alienating women voters. The two vice presidential debates will be key to highlighting what Mr. McCain’s choice may mean to the future governance of America. Senator Biden, a Catholic, will tread a treacherous path between prurience, hypocrisy, condemnation, and condescension.

Mr. McCain, meanwhile, must be left wondering whether what seemed a coup on Saturday remains an unambiguous success this morning. Whatever we conclude about Mrs. Palin, picking her reflects above all on the quality of Mr. McCain’s judgment, which gives us a window into a McCain presidency.

In his book, “Worth the Fighting For,” the senator explained how he made decisions. “I make them as quickly as I can, quicker than the other fellow, if I can. Often my haste is a mistake, but I live with the consequences without complaint.” Are we ready for a president who admits to reaching conclusions too hastily?

nwapshott@nysun.com