HARRISBURG -- State Rep. Daryl Metcalfe, a hard-line Republican from Cranberry, readily acknowledges his standing as the General Assembly's most conservative member.

A legislator since 1998, Mr. Metcalfe, 43, has become the bane of liberal special-interest groups and Democratic lawmakers alike.

He's even been at odds with House Speaker John Perzel, the powerful Republican from Philadelphia, more than any other caucus member.

In a recent analysis by the Commonwealth Foundation, a conservative think tank, of votes cast in 2005, Mr. Metcalfe ranked No. 1 in the Liberty Index, which asked if a bill "expanded or contracted the economic, political or personal liberty of all Pennsylvanians.''

As a leader of the House's vote Tuesday night to define marriage as only between one man and one woman, Mr. Metcalfe found himself in an unusual position, attracting support from a wide range of his colleagues, 136 in all, including 43 Democrats.

Mr. Metcalfe celebrated Tuesday's vote, even as e-mails and phone calls rolled in accusing him of being a bigot and worse.

He got plenty of other messages from constituents who appreciate his efforts to strengthen so-called marriage protection laws.

"I'm working to maintain the liberties the majority of Pennsylvanians seek. They want to protect traditional marriage and raise their children in an environment that doesn't force upon them an opposing view of family," Mr. Metcalfe said.

"Parents don't want their children being taught that a family is composed of Joe and Jack instead of Jack and Jill."

Gay-rights advocates say the bill does nothing to protect marriage and serves only to oppress a minority group.

Mr. Metcalfe and other proponents of the constitutional amendment "claim they're pro-family, but the fact is, they only care about some of Pennsylvania's families," said Stacey Sobel, executive director of the Center for Lesbian and Gay Civil Rights. "If you don't look exactly the way they want families to be, then they don't care if your family is protected, and that's a hard thing to hear."

Since he took office, Mr. Metcalfe has backed efforts to cut state funding to universities that offer domestic-partner benefits and to Philadelphia's effort to promote gay tourism.

"I don't view it as attacking anybody; I view it as protecting traditional family values," Mr. Metcalfe said.

Gay-rights activists say they are baffled that Mr. Metcalfe has spent so much time crafting legislation they say harms their community instead of working on more pressing issues, like tax reform.

"I can't speculate why Daryl Metcalfe does the things he does, but what I can say is that he is shortsighted. People all over the world are becoming more open-minded on this issue and when we look back 40 years from now, he will not be considered a hero," Ms. Sobel said.

Mr. Metcalfe's performance wins plaudits from Nancy Staible of Zelienople, state director of the Concerned Women for America.

"Daryl is a very principled conservative, regardless of the odds. He sticks with his principles. He took a very strong stand against the pay raise,'' she noted.

Mr. Metcalfe, from the growing suburban area north of Pittsburgh, is up-and-coming darling of the Republican right: a military veteran, a husband of 23 years, a sometimes (he admits) overprotective father, the family breadwinner, a member of the National Rifle Association and a Bible-quoting Christian.

Still, he doesn't always toe the party line. A recent House analysis by the online news service Capitolwire last week showed that Mr. Metcalfe led the House GOP in voting against Mr. Perzel so far this session, agreeing with him on only 49 percent of votes.

He was already on the outs with the speaker from last fall, when Mr. Metcalfe repeatedly demanded a vote on a bill to repeal the much-criticized legislative pay raise, which Mr. Metcalfe opposed but Mr. Perzel had favored.

Mr. Perzel finally scheduled the repeal vote but not, he said, in response to Mr. Metcalfe's demands.

Mr. Metcalfe said he has a strong working relationship with Mr. Perzel and most other lawmakers he has gone head-to-head with over issues.

"There are very few legislators that hold grudges from one issue to the next. If you're going to be an effective legislator you recognize that today's battle will have a certain number of allies and tomorrow's battle will have new allies who might have been yesterday's opponents," he said.

Mr. Metcalfe was raised in upstate New York and intended to go to Syracuse University but had a last-minute change of heart after meeting with an Army recruiter nine days after his 17th birthday. He joined the same day and was soon deployed to guard the border between East and West Germany.

He arrived a smart teenager who hadn't always applied himself in school but still managed above-average grades. He left four years later a disciplined military man with a fiancee, now his wife and the mother of his daughter, Lisa, 20.

"Military life teaches people how to work as a team toward a common objective and teaches you to move forward. Even in the face of defeat, you always push forward toward success," he said.