Chris Heinz yesterday campaigned in Pittsburgh for his stepfather, Sen. John F. Kerry, meeting supporters at a personal level and talking about personal matters.

"I will always be grateful to John for the way he came into our family," Heinz, 31, told 25 Kerry supporters at the Shadyside home of real estate developer Richard Pearson.

Kerry revived his mother's interest in life after the death of his father, Sen. John Heinz, in a 1991 airplane crash, Heinz said. Kerry and Teresa Heinz were married in 1995.

"My dad's death took a lot of color out of her sight and a lot of music out of her ears," Heinz said. "John brought that back."

At the intimate "house party," one of nine he attended in Western Pennsylvania yesterday and Tuesday, Heinz said his stepfather had a "slim to small" lead over President Bush in national polls, one he predicted would expand once Kerry started talking more about issues.

The primary purpose of the parties is to enlist campaign volunteers for the fall. More than 500 are active in the "Western Pennsylvania for Kerry" organization, Pearson said. The Bush campaign claims 6,259 volunteers in Western Pennsylvania and 33,807 statewide.

Kerry is likely to name a running mate within two weeks, Heinz said, offering no inside information. "I was very pro-[North Carolina Sen. John] Edwards in the spring," he said. "But now I think we may need someone with stronger credentials on foreign policy."

The New York Post reported yesterday that Kerry is leaning toward former Georgia Sen. Sam Nunn, a longtime chairman of the Senate Armed Services Committee.

Many of the questions for Heinz, whose self-effacing humor charmed many at the house party, concerned his own possible political future. Local Democrats have talked about him as a potential opponent for Rep. Melissa Hart, R-Bradford Woods.

Heinz, who lives in New York City, said he won't make any personal plans until after the November election but added that he is open to returning to Western Pennsylvania.

"Pittsburgh is home," he said.