-- Sen. John F. Kerry appeared likely to announce his vice presidential running mate at a Tuesday morning rally in Pittsburgh, according to Democratic sources, and his aides were poised to launch an elaborate rollout that calls for the Democratic ticket to campaign together throughout the week.

The Democratic nominee remained mum about his choice during a campaign rally and barbecue with his wife, Teresa Heinz Kerry, and about 500 supporters at the couple's estate outside Pittsburgh Monday afternoon. But signs pointed increasingly to a Tuesday announcement.

Media and Democratic Party speculation Monday focused most heavily on Sen. John Edwards (D-N.C.). There was a report that Edwards had interrupted a family vacation in Florida on Thursday to fly to Washington for an evening meeting with Kerry, but it was not clear whether that meeting was definitive.

The senator from Massachusetts has kept his vice presidential decision-making shrouded in secrecy, and conjecture about who is the leading contender has shifted several times recently. That leaves open the possibility that he could pick one of several Democrats believed to be finalists.

That group also includes Rep. Richard A. Gephardt (Mo.), Iowa Gov. Tom Vilsack, Sen. Bob Graham (Fla.) and possibly others. Sen. Joseph R. Biden Jr. (Del.), a close confidant of Kerry's who reportedly was among those under consideration, told reporters on Monday, "I am the most unlikely vice presidential candidate you'll find."

Kerry's team wants maximum exposure for the ticket, but for the sake of secrecy, his running mate is not likely to join Kerry at the Pittsburgh rally, although he may join him later in the day, according to a campaign source.

Kerry and his running mate are expected to campaign together on Wednesday in Ohio and again on Thursday, when the Democrats hold a major fundraising gala in New York. The Democratic ticket will also go to the home state of the vice presidential nominee at the end of the week.

Kerry is scheduled to campaign in Indiana later on Tuesday, then return to the District to appear at the National Education Association's convention. The NEA endorsed Kerry on Monday.

At his picnic Monday, Kerry reminded supporters about the Tuesday rally in Pittsburgh. "At 9 o'clock tomorrow, we're going to have some fun," he said.

It was not clear whether he was dropping a hint or merely playing with a press corps anxious for almost anything related to his vice presidential choice.

Campaign officials cautioned against reading too much into anything Monday, saying the entire roll-out plan could be adjusted to fit Kerry's timetable. "We've got a plan for every day," one adviser said.

Kerry said Monday he had not made a final decision.

"I don't know how people are reporting some of the things they are, but I'll just tell you that I have made no decision at this point in time, and I'm going to continue to keep it a private and personal process until I announce it publicly," Kerry told WTAE-TV in Pittsburgh as the barbecue was breaking up.

Edwards was in Boston on Monday for a pair of fundraisers for Kerry and the Democratic National Committee before returning to Washington but was keeping mum about the vice presidency. But word that he had met with Kerry on Thursday night, first reported by the Associated Press and confirmed by a Democratic source, intensified speculation about his prospects.

Edwards, a first-term senator, would be a popular choice among many rank-and-file Democrats, who were impressed with the unsuccessful campaign he ran for the party's nomination.

Gephardt, the former House Democratic leader, was in Washington on Monday and was captured on camera with his wife, Jane, as they walked their dog, but he offered no hints about whether he knew anything about his chances. Gephardt and Kerry have a solid relationship, and he would bring a wealth of experience to the vice presidency.

Vilsack campaigned Sunday with Kerry in Iowa and was scheduled to leave Monday for a family vacation outside Iowa, according to his staff. Democrats close to Vilsack said Monday they had received no hint about his chances.

At the afternoon picnic, Kerry and his supporters ate hamburgers, hot dogs and kielbasa spiced with an array of Heinz products. The conversation focused almost exclusively on the vice presidency.

"Oh sure, it's on my mind -- everybody's trying to figure out what's what," said Rep. Joseph M. Hoeffel III (D-Pa), who is running for the Senate against Republican Arlen Specter, at Kerry's party. "But the truth is, I don't think he needs a blockbuster pick to unify the party and excite people. I don't think it'll be a surprise."

Hoeffel said that he had no special knowledge of the decision process but that his bet was Vilsack.

Others reportedly on Kerry's short list also had their camps, as reporters sequestered in a bullpen on the side of the lawn beckoned guests over and asked for their thoughts.

"There's a lot of chatter. I think it's gotta be Gephardt," said John A. Brooks, treasurer of the Greater Pennsylvania Regional Council of Carpenters. "But I think he should give Edwards some thought, too. Most people would be satisfied with either."

After he returned in the wee hours on Monday morning from a three-day bus swing through the Midwest, Kerry joined the party just before 3 p.m. with his wife, who is heiress to the ketchup fortune.

The couple spent the early part of the day posing for photographs for Good Housekeeping and Redbook magazines, and being interviewed by the latter.

The party had a more formal feel than the weekend stops in rural towns in Minnesota, Wisconsin and Iowa. Guests here were greeted by a six-piece brass ensemble and a trailer full of Iron City beer to wash down the barbecue fare.

After shaking hands and greeting guests for an hour, Kerry delivered a truncated version of his stump speech, telling supporters -- including a host of elected officials, as well as actor Ed Begley Jr. and former Pittsburgh Steelers running back Franco Harris -- that "the results of this election are more in your hands than in Teresa's and mine."

Balz reported from Washington. Staff writer John Wagner contributed to this report.

Sen. John F. Kerry (D-Mass.) and wife Teresa Heinz Kerry greet supporters during a campaign event at the Heinz family farm.After speaking to backers at the Heinz family farm, Kerry told a TV station regarding his choice for vice president, "I have made no decision at this point."Sen. John Edwards (N.C.)Rep. Richard A. Gephardt (Mo.)Iowa Gov. Tom Vilsack Sen. Bob Graham (Fla.)