Foreign-affairs work is just one of the roles Casey plays in Washington that many people back home might not know about, Democrats say. Some worry that he has done a better job as a senator than in telling voters about it.
Former Gov. Ed Rendell complained on Oct. 16 that Casey had until then run "a non-campaign" against Republican Tom Smith. The inexperienced Smith has climbed from nowhere with $15 million in TV ads to make a race of it Nov. 6.
Not long ago, Casey had seemed a sure shot for a second term.
Rep. Allyson Y. Schwartz (D., Pa.), a friend who has worked with him on expanding children's health care, said she wouldn't "second-guess" his campaign. But crowing isn't the Casey way, she said; building teamwork is.
"He's an awfully nice man," she said. "That sounds benign, but the fact is, in politics, building relationships is important, and being someone who people like matters."
Philadelphia lawyer Thomas A. Leonard, a decades-long friend of the Casey family, said: "I think the idea that he is plain vanilla is not bad. This tea-party notion that compromise is evil is not what we need in Washington. We need bipartisanship and we need people who can reach across the aisle and not be doctrinaire on things."
Casey's quiet performance in Washington has been the campaign focus for Smith. He has labeled Casey a "Senator Zero" who hasn't passed a bill under his own name, "a follower" who goes along with what party leaders say.
Casey has long been popular in Pennsylvania. Son of the late Gov. Robert P. Casey Sr., he was twice elected state auditor general. In his 2004 election as treasurer, he got more votes than any other candidate in state history.
Voters know him well enough, he says, not to buy Smith's portrayal of him.
"He will make that charge; I don't think many people will believe it," Casey said at his office in the Russell Senate Office Building.
It was mid-September, the last day of Senate business before the election. Casey, 52, slender and balding, sat in Room 393 - the office President John F. Kennedy occupied when he was a senator in the 1950s. Kennedy photos hung from the wall. Behind Casey's desk were family pictures, with his wife, Terese, and four daughters.
Casey was due soon for a hearing on confirmation of the U.S. ambassador to Iraq.
"It's not true," he said again of Smith's charge, this time with more emphasis. "When someone makes a statement like that, they better be able to back it up. That's not true. It's a falsehood. But that happens in campaigns."
He ticked off what he has done: "leading the fight" to extend into this year a 2 percent payroll-tax cut for 150 million wage earners; gaining adoption of what he termed "my legislation" to end lobbying abuses; getting $250 million added to the new health-care law for support of "vulnerable" pregnant women. The two candidates have different perspectives on the needs - and importance - of the state's biggest city, Democrats say.
Smith, a coal-mining millionaire who has lived and worked his whole life in a rural corner of Western Pennsylvania, first visited Independence Hall on a campaign trip. Casey taught for a year in North Philadelphia as a Jesuit Volunteer Corps worker right out of college.
Casey went to Obama personally to win $50 million in federal funds to complete dredging of the Delaware River. This will open the Port of Philadelphia to more international shipping and mean thousands of jobs, he says.
In his TV ads, Casey has gone after Smith as too far right for Pennsylvania, a candidate who wants to end taxes on personal investments, who doesn't believe in global warming, who cofounded a tea party group.
(Each man describes himself as "pro-life," but Casey would permit abortions in cases of rape or incest, and to save a mother's life. Smith would advocate for no abortions.)
Personally, Casey has been generous toward his opponent, a high school graduate who has served in elected office only as a township supervisor.
Asked if Smith is prepared to be senator, Casey said: "Oh, sure. There are a lot of different backgrounds that can bring you here. When you get to the point of being the nominee of your party, in very rare instances are you not prepared."
Casey's strength, his allies say, is the open, caring way in which he hears people's concerns. As a candidate for governor in 2002, he often quoted the late Democratic Vice President Hubert H. Humphrey saying that the test of government is how it treats people in the dawn of life, the twilight of life, and the shadows of life.
But in national politics in 2012, the issues have been less about Americans' needs than about taxes and debt. Casey can talk about the latter, too.
"We've got to make the tax code simpler and fairer and, hopefully, bring down the corporate tax rate," he said.
Is Humphrey's notion of a just society out of date? No way, he says.
"I think you've got to have values that undergird the things you do. For me, standing up and fighting for the people who don't have a voice is still a very important value."
Casey said he got his values growing up as the fourth of eight children, and first boy, in a traditional Irish Catholic family.
Like his father, he graduated from College of the Holy Cross, in Massachusetts. The elder Casey was a star on the basketball team. The son, at 6-foot-2, played on the team, too, but wasn't nearly as lithe.
(Eleanor Dezzi, a Democratic operative and Casey friend from Philadelphia, remembers watching him dance at a family wedding: "Talk about robotic!")
Margi Casey McGrath, the eldest Casey sibling, said that even in the family, "it's tough to get Bob to talk about his accomplishments. He's the classic workhorse, as opposed to show horse."
"He has my mother's temperament," she said. "Of all the boys, he has this softer, gentler side to him. . . . The temperature in the room goes down when Bob is in it."
After finishing law school at Catholic University of America, Casey practiced law for six years in Scranton. But as his father's namesake, he seemed destined for politics - and, eventually, to try for governor.
He was auditor general when he lost the 2002 Democratic gubernatorial primary to Rendell. He completed two terms in that office and ran for treasurer in 2004. It was widely assumed he'd run for governor again.
But came 2006.
Up for a third term that year, Republican Rick Santorum was one of the most outspoken and socially conservative members of the Senate, a lightning rod for controversy.
Democrats needed a top candidate, and they turned to Casey. It took him three months to say, yes, he'd run.
"The more I thought about it," he said, "the more I thought I could make greater contributions in the Senate than I could in state government."
The Casey-Santorum race, in a non-presidential year, was one of the most closely watched in the country - basically, a "yes" or "no" referendum on the incumbent.
If Casey wins on Nov. 6, he would be the first Pennsylvania Democrat to get a second Senate term in 50 years - since Joseph S. Clark, in 1962.
Many Democrats think Casey still harbors ambition to be governor one day. Will he ever return to Harrisburg? he was asked.
"I think that's highly unlikely," he said. "In the [Senate], you've got to be willing to stay for a period of time where you can have an impact. I never saw this as a short-term or even one-term stop. I hope I can get that second term and be able to continue to do a lot of work."
Dezzi, the Philadelphia friend, thinks Casey is better off in Washington, where his instinct to share credit and work with all parties is needed most.
"I'm not sure Bob likes being a CEO," she said. "He is a policy wonk."
Sen. Bob Casey
Education: College of
the Holy Cross, 1982; Catholic University of America law school, 1988.
Occupation: U.S. senator, 2007-present; Pennsylvania state treasurer, 2005-6; Pennsylvania auditor general, 1997-2004; practiced law in Scranton, 1991-96.
Family: Wife, Terese;
four daughters: Elyse, Caroline, Julia, Marena.
The senator talks about public service, taxes, and Medicare at www.philly.com/bobcasey
Contact Tom Infield
at 610-313-8205 or email@example.com, or follow on Twitter @tinfield.