Eight days out from the Nov. 3 election that will produce a new Philadelphia district attorney for the first time in 19 years, candidates Seth Williams and Michael Untermeyer are not scheduled to debate.

More than jousting with each other, they are engaged in individual battles with the city's political demography as their campaigns sweep from Manayunk to Mayfair, from Packer Park in deepest South Philadelphia to Parkwood Manor in the Far Northeast.

For Republican Untermeyer, party affiliation is a gargantuan challenge. Of 1,054,000 registered voters in Philadelphia, only 134,000 are Republicans.

His plucky pitch to lure crossover voters at a recent forum in Fairmount Park went like this: "A criminal doesn't ask your political affiliation before he robs you. The D.A.'s office should be apolitical."

For Democrat Williams, the challenges are twofold: keeping his troops hungry despite the complacency-inducing registration advantage, and getting out his vote on a day election officials predict will attract turnout of about 15 percent.

"Some supporters have told me, 'Hey, you can just hang out and win. Why not take your family to Disneyland?' " he recounted recently. "But my opponent is not my Republican opponent. My opponent is apathy."

Williams, 42, worked for 10 years as an assistant district attorney under Lynne M. Abraham, the longtime top prosecutor he wants to succeed. He won the five-man Democratic primary in May with about 41 percent of the vote.

Untermeyer, 58, a lawyer, real estate developer, and former prosecutor, said he switched from the Democratic Party this year to have a clearer shot at the office. He ran unopposed in the Republican primary.

Over the summer, the candidates mostly developed strategy, crafted position papers, and raised money. Separately, they visited prosecutors' offices in New York and San Francisco to examine programs that have successfully dealt with weapons offenses and other crimes. They resumed campaigning in earnest after Labor Day.

On a typical day, Untermeyer began at a busy transit stop by pressing the flesh of early-morning commuters. A few hours later he canvassed rowhouses in Frankford. That night, he spoke to older voters at a Bustleton retirement community.

A devotee of high-tech solutions to criminal-justice problems, Untermeyer contends that electronic monitoring can be revolutionary if used more effectively. It can reduce prison overcrowding and save the city millions of dollars a year, he says, because nonviolent, low-risk offenders can be monitored for about $8 a day instead of the roughly $98-a-day cost of incarceration in a city jail.

Of roughly 9,200 people in Philadelphia prisons on a given day, about 1,500 could be safely supervised on the outside, according to Untermeyer, who derived that figure from conversations with city penal officials.

To illustrate the technology, he had himself outfitted with an ankle-mounted monitor, powered by a GPS and linked to his campaign Web site. For 30 days he invited visitors to the site to track him. In the first 10 days, he said, the site received 17,000 hits.

While agreeing that electronic monitoring can be valuable, Williams has derided Untermeyer's demonstration as "a stunt" to grab media attention.

Because the city's prisons have fixed costs for such needs as maintenance and utilities, Williams says, the savings of which Untermeyer boasts would not be fully realized unless whole prisons were closed, and for the moment that is unrealistic.

The wonkish Untermeyer says his demonstration was designed to highlight the kind of "new ideas" he brings to the table.

"This tool is the future of public safety," he said. "It's what the motor vehicle was to the horse and buggy."

Williams, who is endorsed by several unions, including the 14,600-member Fraternal Order of Police, has the advantage of powerful organizational support - potentially crucial in a low-turnout race.

On Friday his campaign announced that today he will receive the endorsement of Sen. Arlen Specter, a former Philadelphia district attorney.

Williams is broadly backed by African Americans, from rowhouse voters in the city's poorest neighborhoods to J. Whyatt Mondesire, president of the Philadelphia chapter of the NAACP.

If Williams wins, he will be Philadelphia's first African American district attorney.

"A lot of people make a big deal of that," Williams told about 100 African American women at a recent candidates' night sponsored by a black leadership organization.

"That is important. But what's more important to me is that Philadelphia leads the nation in homicides by handgun," he said, with the cadence of a preacher. "That homicide is the leading killer of African American men under 35. And truth be told, we are killing ourselves."

Using a poster-size map and laser pointer, he presented his plan for "community-based prosecution." The idea, he said, is to assign assistant district attorneys to police districts in proportion to where crime occurs, rather than base all of them at the district attorney's headquarters opposite City Hall.

On a typical day, Williams ricocheted among candidates' forums, a meeting of the painters and allied trades union, and a Germantown nursing home where he sought support.

Much of his time is spent fund-raising at events where attendees generally have contributed $100 to $1,000 a head.

In campaign finance reports filed Friday, Williams reported $227,964 in contributions for mid-September through mid-October.

Untermeyer reported $273,924, including a $200,000 personal loan he made to his campaign Oct. 2. His report also listed a $100,000 expenditure for television advertising, which has been running on local cable for two weeks.

Contact staff writer Michael Matza at 215-854-2541 or mmatza@phillynews.com.

Inquirer staff writer Olivia Biagi contributed to this article.