Clinton and Obama launch pushes in Pa.

While Hillary Rodham Clinton and Barack Obama were busy sparring for voters in Texas and Ohio, their Pennsylvania campaign operations were gearing up this weekend with grand openings of local headquarters.

With 51 days to go and only six points separating the two candidates in the latest poll, Pennsylvania's Democratic presidential primary has become serious business.

The results of Tuesday's voting in Texas and Ohio will determine how serious. A victory by Clinton in at least one state probably keeps the race going. But a win by Obama in both could make Pennsylvania's primary - and the 103 Democratic delegates at stake - moot. With Sen. John McCain of Arizona virtually assured the Republican nomination, the GOP primary has little impact.

Obama's Philadelphia headquarters opened at 15th and Sansom Streets yesterday afternoon.

From the street it was hard to spot the small sign on the door for an office four floors up. But inside there was no mistaking you had walked into a grassroots campaign office.

If the coffee spills on the carpet, open bags of Doritos, and plastic folding chairs didn't give it away, the clipboards with Obama's picture on the back in the hands of volunteers eager to register voters did.

"They don't call it the Keystone State for nothing," said volunteer Jordan Dillard, 32, of Mount Airy, adding that he expected every vote to matter.

Clinton headquarters, at Delaware Avenue and Spring Garden Street, will open this afternoon.

Yesterday, the campaign targeted the suburbs, holding meetings in the four counties to train "activists and volunteers" for door-to-door visits, phone banks, house parties and registration drives.

"We are organizing 42 meetings all over the state," said Mark Nevins, Clinton's communication director in Pennsylvania. "It is a logistical miracle."

Nevins said the campaign hoped to sign up 1,500 volunteers this weekend.

Josh Uretsky, cochair of Philadelphians for Obama, said he hoped to sign up more than 1,000 Democrats yesterday.

"People are really excited," he said. "They are excited about him as a candidate and person rather than as somebody to replace Bush."

Victoria Timberlake was excited enough about Obama to give up two days visiting family in the area to register voters. Originally from Upper Darby, she has lived the last 34 years abroad - now in London - but says she always votes.

The world "is longing for America to put a president in office that is as good as the country is," Timberlake said. "It's been a while since that has happened."

Nine-year-old Cualyn Minor of South Philadelphia, at headquarters with his father, said he was impressed with Obama's policy on gun control and wanted to support the candidate.

Cualyn said that he was glad his father had taken him to the Obama event and that "if I was old enough, I would have come without him."

Terry Bremer, 60, of South Philadelphia, said she had been active in presidential and local campaigns as far back as John F. Kennedy's run for president. Now, she said, she sees a "critical need" for a change in the government.

Just feet from the headquarters door, she had helped register two voters in her first 20 minutes.

"It's a really important thing I'm doing today," Bremer said.