BOSTON - John McCain's search for a running mate was remarkable in that it was carried out in secret, concluded with a bang and conducted in sharp contrast to the freewheeling style of his early presidential campaign or his hard-charging Navy days.

The Republican presidential nominee-in-waiting spirited his ultimate choice, Alaska Gov. Sarah Palin, first to Arizona and then to Ohio on a pair of secret corporate jet flights. When her family joined her Thursday night, they stayed in a hotel under an assumed name.

And when it came time to announce Palin's selection on Friday morning in Dayton, Ohio, the news came as a surprise not only to the public, but also to members of her own staff 4,000 miles away in Anchorage.

"Nobody knew about his announcement this morning except (a traveling aide) and the governor's chief of staff, who found out about this last night," said Sharon Leighow, a Palin gubernatorial spokeswoman.

That was precisely McCain's intention.

After securing the Republican presidential nomination in February, the Arizona senator set out to find a running mate who would not only bolster his chances of winning the White House in November but also soothe those concerned that his age might place a question mark over his presidency. He announced the selection of Palin, 44, on his 72nd birthday.

If McCain were to win the general election, he would be the oldest first-term president upon being inaugurated in January.

"The fundamental principle behind any selection of a running mate would be whether that person is fully prepared to take over and shares your values, your principles, your philosophy and your priorities," McCain said on Feb. 8, the day after Mitt Romney, his closest primary rival, quit the race.

McCain also was determined to conduct the search with discretion. He tapped a famed Washington attorney, Arthur B. Culvahouse Jr., a one-time White House counsel to President Reagan, to lead the search. He also limited those with direct knowledge of his deliberations to his wife, Cindy, and a handful of aides including campaign manager Rick Davis and senior advisers Mark Salter and Steve Schmidt.

Schmidt, who assumed control of the campaign's day-to-day operations this summer and instilled a missing sense of discipline, would tell those who asked about the process: "I don't talk about the veep."

In recent weeks, however, McCain and his team began to conduct political soundings as they narrowed their list.

He felt out social conservatives by raising the specter of picking a running mate who favored abortion rights.