It appears Barack Obama is cutting into Hillary Clinton's lead in Pennsylvania, which obviously is not good news for the New York Senator. Polls released in the last two days by Quinnipiac and Rasmussen have shown Clinton's lead now in single digits, and a poll released today by PPP even shows Obama in the lead. Whether or not that poll is accurate, this recent trend shows Clinton is in real trouble.

As Mark Halperin points out in The Page, Clinton doesn't just need to win Pennsylvania, she needs to win it big. Conversely, Obama doesn't need to win the state, but rather just finish close enough that Clinton doesn't pick up a big margin in pledged delegates and popular votes. By RCP's count, Obama currently leads Clinton by more than 160 pledged delegates and 800,000 total votes. Winning by less than 10 points won't seriously cut into Obama's lead.

The next two states to vote -- Indiana and North Carolina -- have a large number of delegates, but the latter appears likely to go for Obama. Clinton needs a big win on April 22, but with less than three weeks to go, that doesn't appear likely.

Here is a chart of the RCP Average in Pennsylvania over the last month: