Hillary Clinton has shored up her lead in Pennsylvania, the next battleground for the Democratic nomination, according to a new poll. The Quinnipiac University survey released this morning gives Clinton a 53 percent to 41 percent lead over Barack Obama about five weeks before the April 22 primary. A Quinnipiac poll in late February said Clinton's lead had shrunk to 49 percent to 43 percent. As in other states, Clinton leads among women, white voters, and older voters, while Obama has an edge among African-American and younger voters and those with college degrees. Pennsylvania, with 158 delegates at stake, is a near must-win for Clinton. The telephone survey of 1,304 likely Democratic voters was conducted March 10-16 and has a margin of error of plus or minus 2.7 percentage points.