Washington  - Pennsylvania, site of the next clash over the Democratic presidential nomination, is a state of somewhat-rusting industry and farming spread among small towns where people go to church on Sundays and love to hunt and fish.

In recent weeks, Senator Barack Obama, 46, has been steadily closing on the double-digit lead that Senator Hillary Clinton, 60, once held among the working-class, largely white Democratic voters of the state - one of the last hopes for rescuing her floundering candidacy.

But over the weekend, a firestorm grew over Obama's comments about small towns in Pennsylvania and their values. He told people at a San Francisco fundraiser that voters in these towns were "bitter" over their economic malaise and might be sceptical about a message of promise "delivered by a 46-year-old black man named Barack Obama."

Obama is the first African-American to be within reach of the White House, and leads Clinton, seeking to be the first woman, by about 164 delegate votes. At the nominating convention in August in Denver, Colorado, the candidate needs 2,024 votes.

"It's not surprising ... they get bitter, they cling to guns or religion or antipathy to people who aren't like them, or anti- immigrant sentiment or anti-trade sentiment as a way to explain their frustrations," he was quoted as saying of Pennsylvania small town voters on the Huffington Post website.

By Saturday, Clinton's troops were out in full force, flooding blogs and e-mails and calling Obama "elitist" and "condescending."

The mayors of Scranton, Sharon, Bethlehem, Wilkes-Barre and Harrisburg told reporters in a phone-in press conference that Obama had trounced the very essence of their state.

"It's telling to me that these remarks were made several thousand miles away from us at a very expensive fundraising campaign event in a very upscale location when he did not think that any of us were ever going to hear what he had to say," said Mayor Steve Reed of Harrisburg.

Obama defended his remarks on the campaign trail in Indiana, saying people were frustrated with lack of health care, lost jobs and Washington's ineffectiveness, and thus they voted on "issues like guns" and "gay marriage" and took "refuge in their faith."

In an interview with the Winston-Salem Journal on Saturday, Obama said he "deeply" regretted any offense, then defended the "underlying truth" of what he said.

Both Clinton and the presumed Republican candidate John McCain hammered Obama over his remarks.

"The people of faith I know don't 'cling to' religion because they're bitter," Clinton said in Indianapolis, Indiana Saturday. "People embrace faith ... because they are spiritually rich."

The fracas injected new life into the six-week lull between the last primary voting in early March and the upcoming Pennsylvania vote. Other controversies in the period have included radical anti- white marks made by Obama's pastor in Chicago, and Hillary's exaggeration of danger during a visit to Bosnia in the 1990s.

Polling puts Clinton 7.3 percentage points ahead of Obama in Pennsylvania, according to an average of nine polls calculated by the internet website, realclearpolitics. com.

Clinton must win Pennsylvania to prove she can capture the major states in general elections on November 4, when Pennsylvania, Ohio, Texas, and California - all states she has won - weigh heavy in the electoral college.

While Obama's strength is seen in Pennsylvania's two major cities, Philadelphia and Pittsburgh, Clinton's lies in the swath of small farming, mining and industrial towns that were home to the so-called Reagan Democrats during the 1980s.

Mayor Robert Lucas of Sharon, Pennsylvania, speculated that Obama might be building a case to explain "why he lost Pennsylvania. Because we're bitter people."

"The furthest thing from the truth is that we are bitter," Lucas said. "Those churches weren't built because we're bitter and we don't go to church because we are bitter. We don't go up to the mountains to hunt because we are bitter."

Pennsylvania holds the largest remaining group of delegates among the seven states that have yet to hold primary elections or caucuses.

The candidates face off on the issue of religion on a special CNN forum after 0005 GMT Monday. (dpa)