Peter Houston Kostmayer (born September 27, 1946) is a Democratic politician who served seven terms in the U.S. House of Representatives from Bucks County, Pennsylvania.
Kostmayer was born in New York City, graduated from West Nottingham Academy in Colora, Maryland, in 1965, and received a B.A. from Columbia University in New York City in 1971.
Kostmayer worked as a reporter from 1971 to 1972. He served as press secretary to Pennsylvania Attorney General J. Shane Cramer from 1972 to 1973 and deputy press secretary to Governor Milton Shapp from 1973 to 1976.
After the retirement of Rep. Edward G. Biester, Jr. in 1976, Kostmayer ran against State Representative John S. Renninger for the open seat. With Jimmy Carter taking Pennsylvania in the 1976 election, Kostmayer won by a 1,300 vote margin. He was the first Democrat to represent traditionally Republican Bucks County in decades.
He won re-election in 1978 against G. Roger Bowers with 61% of the vote. He lost in 1980 with Ronald Reagan sweeping to victory. Republican James Coyne narrowly defeated Kostmayer. Kostmayer married Pamela J. Rosenberg, a mother of two, in 1982.
Kostmayer won back the seat in a 1982 rematch by 2,300 votes. Kostmayer won re-election in 1984 over David Christian by fewer than 4,000 votes. He then enjoyed victories in 1986, 1988 and 1990.
In 1992, Kostmayer faced State Senator James C. Greenwood, who had been a legislative aide to Kostmayer's first opponent, John Renninger. Greenwood defeated Kostmayer with almost 52% of the vote.
In 1982, Kostmayer married Pamela Jones Rosenberg, a young businesswoman with two children from her previous marriage. They divorced in 1991. .
Kostmayer became the Administrator, Region III (Philadelphia) of the Environmental Protection Agency from 1994 to 1995. Later, he served as the President of Zero Population Growth.
He entered the race for Pennsylvania State Senate in 2002 against incumbent Senator Tommy Tomlinson. Kostmayer was defeated, taking 47% in the general election.
Currently, he is the CEO of Citizens Committee for New York City.