PITTSBURGH -- John F. Kerry spent yesterday in isolation at his wife's 90-acre suburban farm, working on his convention acceptance speech amid signs that the presumptive Democratic presidential nominee may announce his choice of a running mate here as early as next Tuesday.

Kerry's public campaign schedule has been disclosed only through Monday, the day after he wraps up a Fourth of July bus tour through the Midwest and then flies back to Pittsburgh. His staff has assembled the telephone numbers and schedules next week for potential running mates, said a top adviser to one of the candidates. Kerry has asked a select few of his closest supporters to reserve Tuesday and Wednesday to travel with the campaign, which would allow for a barnstorming tour by the Democratic duo in advance of a gala fund-raiser next Thursday in New York City.

''We're hearing it's going to be Tuesday," said the adviser, who spoke on the condition that neither he nor his boss be identified.

Speculation has focused on three candidates -- Iowa Governor Tom Vilsack, US Representative Richard A. Gephardt of Missouri, and Senator John Edwards of North Carolina -- but Kerry has limited all concrete information about his search to a tight circle that includes his wife, Teresa Heinz Kerry, and James A. Johnson, the Washington banker heading his search committee. In recent days, Vilsack has been the focus of a media boomlet, but Kerry aides say other candidates including US Senator Joseph R. Biden Jr. of Delaware and former senator Sam Nunn of Georgia remain possible choices.

Whoever the choice and whenever he is announced, the Kerry campaign has already hired the running mate's chief of staff, and is in the final stages of hiring the rest of his staff. The campaign has also reserved a second charter jet and added support staff in its campaign travel office to facilitate travel for the running mate and his entourage, according to Kerry campaign aides.

The Secret Service, meanwhile, has agents ready to begin protecting the nominee as soon as the announcement is made.

Announcing the selection next week would allow Kerry to reveal his pick to maximum fanfare -- before a debate on a constitutional amendment to ban gay marriage that the Senate Republican leadership has scheduled to begin on July 12. The Democratic National Convention begins in Boston on July 26.

Kerry has steadfastly refused to comment on what he has labeled a personal and private process. Yesterday he remained out of public view at his wife's hilltop farmhouse in Fox Chapel, Pa. He planned to stay there through this afternoon, when he was scheduled to fly back to Washington. Tomorrow, he flies to Duluth, Minn., to begin a weekend bus tour of Minnesota, Wisconsin, and Iowa.

During his stops in Iowa, he will be accompanied by Vilsack, who has been vetted by Kerry's search committee. The 53-year-old, who plans to leave office in January 2007 after a self-imposed limit of two terms, is a native of Pittsburgh. Pittsburgh also is the power base of the Heinz family, heirs to the ketchup empire. It is the second-largest city in Pennsylvania, a delegate-rich swing state in November's general election.

A campaign spokesman refused to comment on any speculation about a running mate or the announcement date. Johnson, the search committee head, was traveling in Los Angeles, and Mary Beth Cahill, Kerry's campaign manager, was in Washington.

''We'll have somebody between now and the end of July," said spokesman Michael Meehan.

Kerry arrived in Pittsburgh at 3 a.m. after a swing through Illinois and Arizona. Advisers said he made the unusual choice of leaving the campaign trail yesterday and this morning because it would be one of his last chances to focus on the speech he will deliver July 29 at the convention before the huge media blitz covering his vice presidential pick.

Aboard his campaign plane Tuesday evening, Kerry said that he planned to start from scratch on his latest draft of the convention speech, writing in longhand because he doesn't like using a computer, while drawing on ideas, themes, and drafts from aides that have been percolating for months. Last week an aide carried a proposed draft of the speech written by Kerry's speechwriting team, for the candidate's review. The final prose is expected to be polished by Robert Shrum, Kerry's media consultant and the author of Senator Edward M. Kennedy's ''the dream shall never die" speech to the 1980 Democratic convention.

Speculation that Kerry might also be meeting privately at the farm with running-mate hopefuls drew a few reporters to the foot of the Heinz driveway. Through the day, though, the comings and goings were dominated by landscapers, gardeners, Secret Service agents, and campaign aides in charge of logistics and communications.

Fox Chapel police, called by neighbors who were reportedly concerned about strangers sitting by Mrs. Kerry's driveway, asked to see reporters' press passes and drivers' licenses. An aide to the Kerrys offered a warning that rabid raccoons were known to come out at night.

Kerry returns to the campaign trail tomorrow with speeches in Cloquet, Minn., and Bloomer, Wis., before continuing a southward swing along the Mississippi River in Wisconsin on Saturday and northeastern Iowa on Sunday. That night he flies back to Pittsburgh, where his campaign has said he will stay Monday, the federal holiday for Independence Day. As of yesterday, he had nothing on his schedule for Monday other than plans to spend that night in Pittsburgh.

Among the potential running mates, Edwards was on vacation with his family, Gephardt was in Washington, and Vilsack was in Des Moines. Other possible candidates include Senator Evan Bayh of Indiana, who was in his home state, former Army general Wesley K. Clark of Arkansas, who was in St. Louis for a fund-raiser, and Senator Bob Graham of Florida, who was traveling outside the country.

Recent public opinion polls have shown Edwards the favorite of would-be Democratic voters.

One top Kerry adviser, speaking last week on the condition of anonymity, said, ''If he wants to make the most popular choice, that would be Edwards. If he wanted to do something out of the box, it would be Vilsack."

Gephardt and Edwards are also considered ''safe choices" because their backgrounds have been examined over decades in public service, in Gephardt's case, or during recent Senate and presidential campaigns, in Edwards's case, the adviser said.

Glen Johnson reported from Boston; Patrick Healy reported from Pittsburgh.

© Copyright 2004 Boston Globe Company

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