Will she or won't she?

Go on the attack in tonight's face-off in Philly, that is.

It is the first Democratic debate since Feb. 26 in Cleveland, it comes only six days before the important Pennsylvania primary, and it's a high-profile opportunity for Hillary Clinton to try to reshape a race she is losing.

But it has been the two faces of Hillary in recent debates with Barack Obama. In one, she's gushing about how proud she is to share the stage with him and about how one of the two will make history as the first major party nominee who isn't a white male. In another, she's bashing him on issue after issue and complaining that the press is soft on Obama.

New polls suggest some of the forces that are likely weighing on Clinton's strategy.

A Philadelphia Daily News/Franklin & Marshall survey out today shows that Clinton is holding a narrow lead in Pennsylvania, 46 percent to 40 percent over Obama. But she probably needs a bigger, double-digit win in the Keystone State to really build momentum, so might be tempted to attack Obama, as she has this week over his comments about small-town voters who, bitter about their economic struggles, cling to guns and God.

But a national ABC News/Washington Post survey suggests that Clinton getting tough on Obama is backfiring. Nearly 60 percent of Democratic voters view her unfavorably. Those numbers might argue for staying positive.

Find out which way Clinton goes at 8 p.m. on your local ABC affiliate. The 90-minute debate will air from the National Constitution Center.