The April 8-13 poll shows the New York senator holding a 46 percent to 40 percent lead over her rival from Illinois, down from a 16-point lead in March, the Philadelphia Daily News said Wednesday.
The telephone survey among 914 registered and likely Democrats in Pennsylvania had a 4 percent margin of error.
Analysts cautioned the poll may not reflect the current situation because it does not consider fallout from the row surrounding a recent Obama statement about bitter Americans finding solace in "guns or religion."
The general trend favors Obama, analysts said.
G. Terry Madonna with Franklin & Marshall said Obama gained ground from his Pennsylvania television ads and Clinton suffered by saying she arrived under sniper fire during a 1996 visit to Bosnia.
Clinton beats Obama by 14 points among likely white voters and has a double-digit lead among union members and Catholics. Obama holds a 48 percent lead among non-whites and a 23 percent lead among newly registered voters.