If Barack Obama is to win Pennsylvania today or in November as the party’s eventual nominee, it will be, in part, due to the work of a Pennsylvania senator, Robert Casey Jr.

The image of Mr. Casey, standing atop a Scranton hill wearing a windbreaker and speaking in favor of Mr. Obama, is being shown in heavy rotation in western Pennsylvania for a television ad. The emphasis of the ad is on the presidential candidate’s ability to revive the economy and unite the country.

Mr. Casey, who was elected as a senator in 2006, is a pro-life Democrat. His support of Mr. Obama shows that the Illinois senator can reach beyond the support of African-Americans and white liberals. On Friday, Mr. Casey stood on stage at a rally outside Heinz Field in Pittsburgh with former members of the Pittsburgh Steelers who played in the 1970s and early 1980s, when they won four superbowls. The popularity of the team during that time made it possible for Pennsylvanians to transcend ethnic, religious, and political divides.

“This crowd is young and old and white and black and focused on the future,” Mr. Casey said to cheers from the audience as he stood beside legendary running back Franco Harris.

Mr. Obama often talks about working with Americans across political lines. In recent weeks as Mr. Obama’s campaign has begun to resemble a more traditionally liberal Democratic candidacy, Mr. Casey’s support could help to counteract that. A conservative Democrat on social issues, Mr. Casey is Catholic and was educated at Holy Cross and the Catholic University of America.

Mr. Casey’s family, who is also Catholic, has had a rocky time with members of his own party over abortion. Back in 1992, his father, Robert Casey, then the governor of Pennsylvania and also pro-life, never made it onto the speaking program of the Democratic convention that nominated Bill Clinton due to his position on abortion.

When Governor Rendell, who supports Senator Clinton, defeated Mr. Casey Jr., in the fight to be the Democratic nominee for governor in 2002, the National Abortion Rights Action League and Planned Parenthood campaigned against the unsuccessful candidate.

Mr. Casey said Mr. Obama, who is pro-choice, is drawing support from Pennsylvanians of different political stripes. “I have constituents who would never dream of voting for a Democrat who are not only saying they’re going to do it, they’re being very public about it. They’re Independents and Republicans,” Mr. Casey told the Sun after his speech. “I think he’s putting together the kind of coalition to win not just a general election but to govern.”

While Messrs. Casey and Obama hold opposing views on abortion, Mr. Casey praised the Illinois senator for his handling of that difference. “We can disagree on the issue, which he and I do, but we can also reach common ground on things like family planning and trying to reduce the number of abortions and trying to help pregnant women. I don’t think either party’s doing a good job on that,” Mr. Casey said.

Mr. Casey contends that Mr. Obama will be able to attract voters on the basis of faith. For example, Mr. Obama appeared with Senator Brownback, a Republican senator of Kansas, at an evangelical church in California, the Saddleback Church.

“For a lot of voters, they want to know a lot about who you are, what you believe, what your values are and what you think about your own faith and are you a candidate willing to listen to people talk about their faith,” said Mr. Casey. “I think he’s shown a great ability to do that.”

Mr. Obama’s campaign has, however, been damaged due to two recent incidents that revolve around his faith and others: the comments of his former pastor, the Reverend Jeremiah Wright and his own statement that working class and small town Americans are “bitter” and “cling to religion.”

Asked whether voters interested in faith might be put off by Mr. Obama’s “bitter” comment, Mr. Casey said, “I think people process a lot of information in a campaign … I think they’re going to make the full measure of him and I think he’ll do well.”

At a campaign event where voters seemed to be more interested in football stars than politicians, Mr. Casey took every opportunity to make his case for Mr. Obama. He was the last one to shake hands with Obama supporters. “I’m not sure if he’ll win but I think he’ll have a good foundation for the general election here,” Mr. Casey said of Mr. Obama’s chances today.

If Mr. Obama wins in Pennsylvania or even performs above expectations, Mr. Casey’s reputation in national circles will rise as well although he is too green to be considered as a potential running mate. Mr. Obama does need someone with Mr. Casey’s credentials in the Catholic and the blue-collar groups, but he also requires a person with foreign policy and military experience, which Mr. Casey has minimal experience with. Even so, the Pennsylvania senator is poised to reap some benefit from a strong showing by Mr. Obama.

Mr. Gitell (gitell.com) is a contributing editor of The New York Sun.