Near the end of a virtual town-hall meeting last night with suburban Philadelphia voters, conducted by telephone, Republican presidential candidate John McCain got a question that went right to the heart of the matter.

A woman who identified herself as Sally from Mortonville, Chester County, said she had once favored Democrat Barack Obama but was now confused about whom to vote for. Make your case, she told McCain.

The Arizona senator replied that the distinctions between himself and Obama basically came down to "how we view the role of government."

He mentioned their differences on the Iraq war. Then he noted the likely vacancies to come on the U.S. Supreme Court and talked about appointing justices "who are qualified but also strictly interpret the Constitution."

All that was good enough to close the deal, Sally said, and McCain thanked her once, then again as he signed off.

"Every vote counts," said the candidate, who was calling in from West Virginia, "and I'm glad I got one tonight, in Sally."

For 45 minutes last night, McCain talked via conference call with a number of Southeastern Pennsylvania voters, all of them chosen, according to his campaign, because they are registered as independents.

In his opening remarks, he talked about energy, Iraq, and the importance of Pennsylvania in electoral calculus. In responding to questions from eight of the voters on the call, he talked about education, partisanship, Social Security and Medicare, and the danger sometimes posed by products imported from other countries.

"When a toy with arsenic in it comes in from China," McCain said, referring to a controversy that erupted last year, "I think that should be the last toy."

But while calling for tougher enforcement of trade agreements, he reiterated his support for expanded international commerce, noting that exports were one of the few bright spots in the current U.S. economy.

In answer to a question on energy conservation, McCain toned down the ridicule he has heaped on Obama in the last week, ever since the Democrat said that properly inflated tires could save as much gas as would be produced by expanded off-shore drilling - which McCain advocates.

"I don't disagree with that; the American Automobile Association strongly recommends it," McCain said of proper tire inflation. "But I also don't think that's a way to become energy-independent."

The conference call was part of the concerted effort McCain has made this summer to make inroads in Pennsylvania. The state voted Democratic in the last four presidential elections, but Obama lost the April primary to Hillary Rodham Clinton.

McCain, who was in Montgomery County on Monday, has made numerous visits to the state over the last two months, with more expected, and has spent heavily on television commercials.

Contact senior writer Larry Eichel at 215-854-2415 or leichel@phillynews.com.