Hillary Clinton's solid Pennsylvania primary victory may stem more from Democratic demographics than anything that happened in the bitter six-week campaign leading up to it.

After all, the New York senator's 9-point winning margin and showing with most major constituencies were almost identical to her performance seven weeks ago in neighboring Ohio.

The initial reaction from pundits and the media is that she did more to keep her candidacy alive than to reduce the likelihood that Barack Obama ultimately will be the Democratic nominee to face Republican John McCain.

But Obama's failure to make more than modest inroads into groups that form the Democratic core only will encourage the questions about his patriotism and ties to controversial associates that marked the campaign.

McCain made that quite clear Sunday when he was asked on ABC's "This Week with George Stephanopoulos" if he believed that Obama "shares" his sense of patriotism.

"I'm sure he's very patriotic," the Arizona senator began. Then, without prompting, he raised the question of Obama's relationship with onetime radical leader William Ayers, denouncing the Illinois senator for his closeness to "an unrepentant terrorist."

Another sign that the GOP sees political mileage in this approach is Wednesday's unveiling by the North Carolina Republican Party — over McCain's objections — of an ad that questions the "judgment" of the two top Democratic gubernatorial candidates for backing Obama and shows a clip of the Rev. Jeremiah Wright.

Still, despite their prevalence in last week's televised debate and in day-to-day campaign coverage, there remains doubt how much these issues affected the outcome.

Obama did marginally better in Pennsylvania than in Ohio among white voters and men, his final deficit was less than in early polls, voters saw Clinton's campaign as the more negative, and most Democrats said race was not a factor in their votes.

Besides, when exit pollsters asked if voters felt the two were interested in "people like you," they rated them the same.

Still, about a quarter of the Clinton voters said they would vote for McCain if she weren't the nominee, and 18 percent said they would stay home in November.

That would be disastrous for Obama, but the likelihood is that those numbers would fall in the general election, when contrasts between the nominees' key positions became evident.

Even as Clinton remains stronger among basic groups that the party needs in order to win such key states as Ohio and Pennsylvania, Obama continues to show that his appeal extends beyond those groups in a way that is also necessary for victory, since core Democrats are not enough to win an election.

That was evident in Pennsylvania in his strong support among the 300,000 new Democrats who have joined the party since January. In a broader context, he continues to show almost daily an appeal beyond liberal Democrats that Clinton can't match.

Wednesday, Gov. Brad Henry of Oklahoma, the conservative Democratic governor of a "red" state, announced his support for Obama.

He joins, from the last week, two respected conservative Democrats — former Sens. Sam Nunn of Georgia and David Boren of Oklahoma — and two notable Republicans — William Ruckelshaus, a key figure in past Republican administrations; and Julie Nixon Eisenhower, the daughter of former President Richard Nixon and the sister-in-law of another Obama backer, Susan Eisenhower.

None has the political clout that Gov. Edward Rendell gave Clinton in Pennsylvania or Sen. Evan Bayh hopes to provide May 6 in Indiana.

But they suggest the kind of coalition that remains possible for Obama, assuming he can survive the fierce challenge of the former first lady and legitimate questions about who he is and what he believes.

Carl P. Leubsdorf is Washington bureau chief of the Dallas Morning News. Reach him at cleubsdorf@dallasnews.com.