Pennsylvania Democrats hoping to catch a glimpse of their favorite presidential candidate shouldn't have to worry.

Hillary Clinton's first campaign visit to Pittsburgh could be next week. "It will be within in the next five to seven days," her Pennsylvania spokesman, Mark Nevins, said Wednesday.

And it’s likely voters "will be able to have breakfast with Barack Obama at your local diner," said state Democratic chairman T.J. Rooney.

By winning Tuesday's two big primaries in Texas and Ohio, Clinton kept alive her campaign and snapped Obama's string of 11 straight victories. That shifts the battleground to Pennsylvania in the weeks leading to the state's April 22 primary.

"Pennsylvania is about to become a marathon that may turn into out-and-out war between Clinton and Obama," said University of Virginia political science professor Larry Sabato. "It will be a long twilight struggle with millions and millions of dollars spent."

After a caucus Saturday in Wyoming and Tuesday's Mississippi primary, Clinton and Obama will face a six-week stretch of bare-knuckle campaigning in the Keystone State -- the last big prize of the primary season and another "must-win" for Clinton who still trails Obama in the delegate count, Sabato said.

Pennsylvanians should prepare for an onslaught of robo-calls, targeted direct mail, e-mails, invitations to town hall meetings and campaign signs on every street corner, said Democratic strategist Mark Siegel.

It's the kind of hand-to-hand, delegate-by-delegate combat that makes Republicans giddy.

"She can’t put him away, and he can’t put her way," Sabato said. "Meanwhile, while nobody is looking, John McCain will be organizing, raising money and preparing for the fall."

McCain clinched the Republican nomination Tuesday as his last remaining opponent, former Arkansas Gov. Mike Huckabee, dropped out of the race. McCain, an Arizona senator, yesterday visited the White House to accept President Bush's endorsement.

The last time the Pennsylvania primary made a difference was in 1976, when former Georgia Gov. Jimmy Carter's victory cleared the way for him to win the nomination and, in turn, the presidency.

Pennsylvania's unexpected relevance -- after a failed effort last year to move up the primary -- will pay dividends for residents. The candidates will be forced to focus on issues important to the people, and they'll give the tourism industry a boost as campaign operatives and members of the national media snap up hotel rooms across the state, said Brian Schaffner, a political science professor at American University.

The nation's sixth most populous state, Pennsylvania bears many similarities to Ohio, where Clinton defeated Obama by 10 points Tuesday. It's a Rust Belt state largely abandoned by the once-mighty steel, coal and railroad industries.

"Look for lots of talk about NAFTA," Schaffner said.

Obama and Clinton have both said they want to re-evaluate and renegotiate the North American Free Trade Agreement, which became a contentious issue in the final days of the campaigns in Ohio and Texas.

Pennsylvania's comparatively high union membership -- 13.5 percent of state wage earners, compared to 12 percent nationally -- and large elderly population make it fertile ground for Clinton, whose political base is anchored by older white voters and blue-collar workers. The state AFL-CIO estimates a third of registered voters live in union households.

Clinton's daughter Chelsea campaigned for her mother in Philadelphia yesterday. The campaign was setting up a headquarters in Pittsburgh, operating out of a temporary office in the American Federation of State, County and Municipal Employees building Downtown.

Obama likely will not visit Pennsylvania until after Tuesday's primary in Mississippi.

"After that, expect to see him non-stop," said Obama spokesman Sean Smith. Continued...