PEOPLE in Pennsylvania, at least Republicans, aren’t as politically correct as the citizens of New York. Sen. Arlen Specter was the speaker yesterday at the Rainbow Room for the annual meeting of the Commonwealth Club, a group of Keystone State Republicans who come to Manhattan every yuletide. A witness reports Specter began by asking if anyone in the room was Polish. About 10 guests out of hundreds there raised their hands. Specter deemed the number insignificant and forged ahead with some supposedly funny Polish jokes, including the old one about the man who interrupted him once, saying, “Hey, careful. I’m Polish!” Specter said he responded, “That’s OK – I’ll tell it more slowly.” Specter also told two other tasteless jokes in the same Polish vein. “No one walked out, but it was offensive,” said our source. “I was offended, and I’m not Polish.”