The three Democrats vying to take on Rep. Tim Murphy this fall agree on at least one thing: Mr. Murphy, an Upper St. Clair Republican, hasn't faced serious opposition since he first won his seat in 2002.

That, they argue, is about to change.

The national Democratic Party views Mr. Murphy's District 18 -- which covers parts of Allegheny, Washington and Westmoreland counties -- as a compelling target this year because of a growing registration edge and voter angst over the economy and the war in Iraq.

First, however, party members from the district need to select a candidate in the April 22 primary election.

The three contenders are: Beth Hafer, 35, of Mt. Lebanon, vice president of Hafer & Associates; Steve O'Donnell, 62, of Monroeville, a businessman; and Brien Wall, 59, of Upper St. Clair, also a businessman.

Mr. Murphy has no opponent in the GOP primary.

Ms. Hafer comes to the race with significant name recognition, thanks to her mother, Barbara Hafer, a former Allegheny County commissioner, state treasurer and state auditor general.

But Ms. Hafer argues that she has already built up a strong resume of her own, including work in the pension fund advisory group at Legg Mason real estate services in Philadelphia and a stint as a teacher at Winchester-Thurston School and Moon Area Middle School.

She now works for her mother's government consulting firm. Ms. Hafer has a bachelor's degree in general science from Penn State and a master's degree in education from Duquesne University.

She decided to make her first run for public office because she thinks the federal government has "lost its way."

This is Mr. O'Donnell's second run for office. In 2006, he came within 240 votes of defeating state Rep. Joe Markosek in the primary race for the House District 25 Democratic nomination.

Mr. O'Donnell said the race taught him how to be a tough competitor, and he cites his varied work history as good preparation for Congress.

After serving in the Navy in the 1960s, Mr. O'Donnell received a bachelor's degree in history at Duquesne University and a master's degree in rehabilitation counseling from West Virginia University.

He has been a counselor at State Correctional Institution Pittsburgh, executive director of the Westmoreland County Chapter of the Pennsylvania Association of Retarded Citizens and president and chief executive officer of a company providing services to adults with mental retardation.

Mr. O'Donnell was also a co-founder of a holding company that invests in real estate and other businesses.

"I believe that this Republican administration -- and Tim Murphy is part of this administration -- may be one of the worst administrations that I've witnessed in my lifetime," Mr. O'Donnell said, citing the war in Iraq, the worsening economy and tens of millions of Americans without health insurance.

Mr. Wall said his concern for working-class families has pushed him to run. A native of Brookline, he served as a military policeman at West Point during the Vietnam era. He has a bachelor's degree in economics from the Indiana University of Pennsylvania.

For more than 20 years, Mr. Wall has worked as a family business specialist at Massachusetts Mutual Life Insurance Co. He is a member of the Allegheny County Democratic Committee.

In 1996, he won a Courage to Come Back Award from the St. Francis Health Foundation after overcoming alcoholism.

There are few major policy differences among the candidates. All three, for instance, oppose the Iraq war.

During a recent meeting with the Post-Gazette editorial board, Mr. O'Donnell said he would like to see American forces pull out from Iraq within 18 months. He said the U.S. had no "moral authority" there because the Bush administration's stated reasons for the war, such as the search for Saddam Hussein's weapons of mass destruction, turned out to be false.

Mr. Wall also supports a withdrawal, but he suggested that a public timeline would be dangerous.

"We don't need to put that timetable on the front page of the Post-Gazette," he said.

Ms. Hafer said her primary concern is the safety of U.S. troops. Her brother is a Navy SEAL.

"I'd like to leave as soon as possible without jeopardizing the troops," she said.

Ms. Hafer said the U.S. government should invest more money in rebuilding Iraq's infrastructure to pacify the country.

All favor a complete overhaul of the U.S. health care system. Mr. O'Donnell is calling for a universal, single-payer plan that could take up to 10 years to put in place. But he argues that such a change would save huge sums for American businesses that now cover their employees' health costs.

Some of the expense of new system, he said, could be covered by taxes, including a tax on stock transfers.

Mr. Wall suggested modeling a universal system on Medicare, and Ms. Hafer said her own experiences with her father-in-law's health problems had convinced her of the need for a single-payer system.

Ms. Hafer and Mr. O'Donnell exchanged some heated words after a debate before the League of Woman Voters last week, with Ms. Hafer accusing Mr. O'Donnell of mismanaging a Greensburg nonprofit agency, Life Service Systems, which went bankrupt in 1997.

"I'm proud to say I have a strong record on managing taxpayer money," Ms. Hafer said, referring to her work at her mother's firm. "My opponent, on the other hand, does not."

Mr. O'Donnell said he had left his post as the head of the agency before a new board of directors decided to file for bankruptcy. A bankruptcy court trustee blamed the agency's demise on his successors.

"Hafer knows or should know that," he said. "She is misleading the public."

Not surprisingly, the candidates' differ most strongly on who would make the strongest challenger for Mr. Murphy. Any eventual winner will need a sizeable war chest to take on the incumbent, who had raised more than $600,000 by the end of last year, according to the Center for Responsive Politics.

Mr. O'Donnell raised more than $260,000 over the same time period, giving him a substantial edge among the Democrats. He was able to contribute most of the money to his own campaign, although he says he'll be drawing on a much larger number of supporters in a general campaign.

Ms. Hafer, who has raised nearly $150,000 to date, said she can count on more donors.

Mr. Wall said he has raised about $40,000 so far, but he said he could turn that into a plus on the campaign trail.

"I'm not from the privileged class," he said.

Mr. O'Donnell and Ms. Hafer also cite their own modest roots as motivators in the race.