Sen. Barack Obama continues to eat away at the lead of Sen. Hillary Clinton’s in Pennsylvania, polls from Quinnipiac University and Rasmussen Reports show.

The Quinnipac survey showed the New York senator’s lead over her Illinois counterpart now stands at 6 points in the new poll, 50-44 percent.

That compares to a 9-point lead Hillary Clinton held in a similar survey released last week, and an 11-point lead in a Quinnipiac survey last month.

A Rasmussen poll gave her a similar edge, 48-43 percent.

For a broader look, six Pennsylvania primary polls taken in the month of April show Clinton leads of 3, 5, 18, 5, 6 and 3, for an average of 6.7 percent.

Polls are just polls (we’ve seen how wrong they often are), and the primary is still 13 days away, but Barack Obama is clearly making significant headway, leading some observers to think he may be planning a knockout strategy.

It helps that he’s been able to outspend Hillary Clinton 3-to-1 just on TV ads to help get his name and message out there. Obama has gotten some help from the Service Employees International Union, which is also spending heavily.

Clinton, however, traditionally does well with white, working-class voters, a group with considerable influence in this closed Pennsylvania primary.

The expectations may end up being as important as the result.

Does a win by Clinton by a close margin (say, 53-47 percent) give Barack Obama the momentum, as he once trailed by 20? Or does it mean she withstood yet another assault amid being outspent and urged by some Dems to get out?