(CNN) - Pennsylvania Sen. Bob Casey will announce his support of Barack Obama's White House bid Friday, an endorsement that could give the Illinois senator a boost in the crucial primary state that votes April 22.
The official endorsement is expected to come later Friday as Obama begins a week-long campaign-swing through the state. Several recent polls suggest Hillary Clinton appears to hold a double-digit lead there.
Casey is a first-term senator and son of a popular former governor of the state, Bob Casey, Sr. A prominent catholic, Casey's support could help Obama make inroads among catholic voters in the state - a voting bloc that has favored Clinton in most other primary contests.
In 2002, Casey lost a hard-fought gubernatorial primary contest against Pennsylvania Gov. Ed Rendell, now an ardent supporter of Hillary Clinton's White House bid.
- CNN Ticker Producer Alexander Mooney