(CNN) - As bickering has increased in the Democratic nomination race, Sen. Hillary Clinton faces pressure to drop out and Sen. Barack Obama is working hard to best Clinton in Pennsylvania's upcoming primary.
In the lastest episode of CNN=Politics Daily, Jessica Yellin reports on how Clinton has responded to pressure from high-ranking Obama supporters in the Democratic Party who would like Clinton to end her presidential bid.
Despite Obama's overall lead in the delegate count and in pledged delegates awarded so far, the Illinois senator faces an uphill battle in Pennsylvania. Senior Political Analyst Bill Schneider reports on a key endorsement Obama received Friday in Pennsylvania. Schneider explains how the endorsement may help Obama with a demographic he must win over in order to win the next primary.
Obama's front-runner status has brought new scrutiny and a new label - 'liberal.' Randi Kaye reports on Obama's legislative record and on claims that he leans to the left on the political spectrum.
While Obama and Clinton continue to battle it out for their party's nod, Sen. John McCain is seeking to define himself in the eyes of the electorate. Mary Snow reports on McCain's new ad campaign and a multi-state bus tour the Arizona senator will take next week in an effort to style himself as the most attractive option for voters in November.
Finally, it's Friday so it's time for Jennifer Mikell's Trail Mix - a look at this week's most memorable moments in the presidential campaign.
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–CNN Associate Producer Martina Stewart