It’s been a long time since Pennsylvania was within reach of a Republican presidential candidate, but Quinnipiac becomes the latest pollster to put Mitt Romney nearly within the margin of error in the Keystone State.  In a single month, Romney gained eight points on Barack Obama in a state that Democrats have to keep in their column to have any chance of holding the White House, and Obama now only leads by four:

Gov. Mitt Romney has narrowed a 12-point gap with President Barack Obama and now trails the president 50 – 46 percent among Pennsylvania likely voters, according to a Quinnipiac University poll released today.

This compares to a 54 – 42 percent Obama lead in a September 26 survey by the independent Quinnipiac (KWIN-uh-pe-ack) University.

In today’s survey, men back Romney 54 – 43 percent, compared to a 49 – 48 percent split September 26. Women back Obama 57 – 39 percent, little changed from last month. White voters back Romney 53 – 43 percent while black voters back Obama 97 – 1 percent. White Catholic voters go Republican 56 – 43 percent. Voters with college degrees back the president 54 – 43 percent while voters without degrees are divided with 49 percent for Obama and 47 percent for Romney.

National Journal notes the big shift in Romney’s favor as well in another poll:

The survey also squares with another recent Pennsylvania survey that reported Romney gains. A Muhlenberg College/Morning Call poll of likely voters, conducted from Oct. 10 through Oct. 14 with a margin of error of 5 percentage points, found Obama leading Romney by only 4 points, 49 percent to 45 percent. That was down from an 7-point advantage for the president from the same survey taken in late September.

RCP now has the Obama lead in its Pennsylvania average down to 5%, with three of the polls — Quinnipiac, Morning Call. and Susquehanna — under that range. The sample in the Q-poll is a D+8, 39/31/26; the exit polls from 2008 were D+7 at 44/37/18, and but 2010 was much closer, with a D+3 at 40/37/23.  Democrats have a large registration advantage, but the turnout model here appears to significantly underrepresent Republicans while getting Democrats about right.  Since independents favored Obama in this poll by seven, that might be a significant point to keep in mind.

Pennsylvania is now definitely at least in play.  Obama has to keep spending more money on defense in the state in order to keep Romney from stealing the state away, becoming the first Republican to take it since George H. W. Bush in 1988.  If Romney breaches this firewall, it’s going to be an early night on Election Day.