With one week remaining until the Pennsylvania primary, New York Sen. Hillary Clinton has stalled Illinois Sen. Barack Obama's drive in the Pennsylvania Democratic primary and holds a 50 to 44 percent lead among likely primary voters, according to a Quinnipiac University poll released this morning.

The results are unchanged from April 8.

There also was no noticeable change in polling following widespread media reports on Sen. Obama's "bitter" comments about Pennsylvania voters.

But in this latest survey of 2,103 likely Democratic primary voters by the independent Quinnipiac University, 26 percent of Clinton supporters would switch to Arizona Sen. John McCain, the Republican, in November if Obama were the Democratic nominee.

Nineteen percent of Sen. Obama backers would switch to Sen. McCain if Sen. Clinton were the Democratic nominee.

A look at other groups shows:

• White voters back Sen. Clinton, 57 to 37 percent, compared to 56 to 38 percent last week;

• Black voters back Sen. Obama, 86 to 8 percent, compared to 75 to 17 percent last week;

• Women back Sen. Clinton, 54 to 40 percent, unchanged from 54 to 41 percent last week;

• Men lean toward Sen. Obama, 51 to 43 percent, compared to a 48 to 44 percent last week;

• Voters younger than 45 go with Sen. Obama, 55 to 39 percent, while older voters back Sen. Clinton, 55 to 40 percent.

"Sen. Hillary Clinton is fighting off Sen. Barack Obama's drive to make it a close race in the Pennsylvania Democratic primary, holding the six-point edge she had a week ago. She seems to have halted the erosion of whites and white women in particular from her campaign," said Clay F. Richards, assistant director of the Quinnipiac University Polling Institute. "She even gained back some ground in the Philadelphia suburbs -- the area where elections are won and lost in the Keystone State. She now trails Obama by just two points in this critical area, while she was 11 points behind a week ago."