In a state that pollsters and analysts call Ohio on steroids (and thus tailor-made for Hillary Clinton), Barack Obama is coming on strong.

So much so that some observers wonder if the former First Lady’s unraveling is in the offing, writes Philadelphia Inquirer columnist John Baer.

His campaign yesterday announced that it raised $40 million in March. More money means more TV, and Obama’s clearly clubbing Clinton.

More significantly, though, has been his ground war.

For the past six days, Barack Obama has crisscrossed the sprawling state on a bus tour with stops in places that should be hers or the GOP’s.

He went to blue-collar Johnstown, home of a big-name Hillary backer, U.S. Rep. John Murtha. He went to hardscrabble Scranton, birth and burial place of Hillary’s father, Hugh Rodham. He went to rural, conservative Lancaster County.

Point is, he’s running hard in a state some said he’d write off since it’s so, well, Clinton’s. It’s also a state where much of the establishment - Murtha, Gov. Ed Rendell, Philadelphia Mayor Michael Nutter, endorses Clinton.

An average of multiple new polls, including one even putting him slightly ahead, show he has closed the gap considerably, and trails by an average of 5-6 percent. Not bad when you used to be down 10, 15, even 26 in one survey.

Barack Obama’s Keystone State resurgence has triggered speculation that he may be going for the knockout on April 22 - even the most ardent Clinton backers have said she needs to win the Pennsylvania primary to stay in the race.

But the knockout strategy carries its own risks.

With a stark imbalance between the two Democrats evident at last, it is tempting, certainly, for Obama to launch a final assault. But there are still limits to what he can expect to accomplish with this state’s unique demographic mix.

In other words, despite his significant gains in name recognition, large numbers of Catholics, blue-collar workers, seniors and women who traditionally vote in the Democratic primary lean toward Clinton - and that will be hard to change.

There is risk inherent in launching a full-scale offensive to score an upset, as well. As the expectations go today, Hillary Clinton likely needs a relatively large win to seize any real momentum from the Keystone State election.

If he makes a noticeably strong big for a win and falls short, Clinton then could say she withstood his assault, bolstering her claim that she is the stronger of the two (the lowering expectations game manifesting itself in vintage fashion).

There’s also the nature of the man himself.

Over the past year, presidential candidate Barack Obama has proved himself to be charismatic, inspirational, resilient and a debt counter-puncher.

But he has rarely gone on offense, and to defeat Clinton in Pennsylvania he might have to. The catch-22? It’s Howard Dean’s worst nightmare - divided Democrats bitter over an all-out assault by one to vanquish the other for good.