Asked what role US Rep. John Olver plays in the 10-member Massachusetts congressional delegation, Rep. Michael Capuano of Somerville puts it very simply: “Money.”

Ask Olver about his role and the answer is a little less succinct. OK, make that a lot less succinct. In fact, prepare for a long lecture about how the congressional appropriations process works, how it integrates with congressional authorizing committees, and how it’s not maybe quite as powerful as some say it is to have a seat on the House Appropriations Committee.

But Olver seems to relish his role as the Bay State’s money man — that is, our representative on “Approps,” as the committee that oversees $1 trillion in discretionary federal spending is called in Washington. He’s even a cardinal, to use the nickname given to chairs of the 12 subcommittees of Appropriations, and his subcommittee is a biggie, covering both transportation and housing.

The former University of Massachusetts chemistry professor is a major power broker in Washington, albeit one with a very low profile. He rarely sponsors legislation or mounts a soapbox to address big national issues.

“There’s a substantial amount of responsibility,” he says of his position. “What one does in the Appropriations Committee is try to serve the whole caucus,” referring to all Democrats in the House.

For Olver, that’s a pointed remark, given that some of his Bay State colleagues once accused him of not looking out for anyone but himself. In 1999, the now-deceased former dean of the delegation, Joseph Moakley of South Boston, derided Olver for failing to help out the rest of the state. “Some people are born salesmen, others are born librarians,” he told the Boston Herald at the time.

But according to interviews with his colleagues, and a review of Olver’s priorities on the Appropriations Committee, it seems Olver has learned his lesson.

He’s certainly kept his eye on the money. According to the nonpartisan Citizens Against Government Waste, he was one of the most prolific sponsors of local projects in the federal budget last year, earmarking some $71.3 million for 63 projects across Massachusetts. That placed him 37th among the House’s 435 members but first among Bay State representatives. Although many of those earmarks were directed to his district, Olver did collaborate with five of the other nine Bay State representatives on specific projects, and his focus on Amtrak and public housing has played to the benefit of the more populated eastern sections of the state.

Now the fiercest criticism he’s receiving is from fiscal conservatives. His tally of earmarks, for example, isn’t a recognition Citizens Against Government Waste considers an honor. The group ranks representatives for their proclivity for earmarking funding in its annual “pig book,” which alludes to the derogatory term often given to such projects: pork barrel funding. The group argues that local projects should be funded at the local level, not with federal tax dollars.

Olver brushes off the criticism, pointing out that earmarks — which came to $17 billion this fiscal year — are a tiny part of the overall budget and have their place in the process, especially in helping rural and less well-to-do regions.

“We have a clear idea of where the needs are in our districts,” he says of congressmen.

Olver says Washington agencies don’t know what’s happening on the ground in individual districts and, as a result, communities often garner money not because they are deserving but because they have better grant writers. Of course, the same argument could easily be turned on its head: Those districts represented by powerful lawmakers attract more federal money not because they are more deserving but because they have better political connections.

But in their successful bid for control of the House in 2006, Democrats ran, at least partially, by stressing how much their GOP colleagues had abused the earmarking process. After assuming power, the Democrats imposed new disclosure rules — one of the reasons analysts can say with certainty how prolific an earmarker Olver has been. The value of earmarks has also fallen considerably from the peak of $52 billion in 2005.

Olver’s proficiency in bringing home the bacon hasn’t lost him any friends in western Massachusetts. “He’s been given the moniker as the biggest pork barreler from Massachusetts, which we’re very thankful for,” says Michael Sullivan, the mayor of Holyoke, with a laugh. “We’re happy we have a congressman who goes to Washington and understands our community and does what he needs to do to help us.”

Sullivan specifically cites Olver’s work in bringing housing grants to Holyoke, as well as his efforts to expand train service in the region. That’s just the tip of the iceberg. In recent years, Olver has found money in the federal budget for bike paths, open space preservation, and countless transportation projects. He’s also directed millions back to his former employer, the University of Massachusetts at Amherst.

A huge ally of Amtrak — he will gladly regale audiences with lengthy arguments about the virtue of expanded rail service — Olver has used his spot on Approps to beat back efforts by President George W. Bush to cut funding for the perennially money-losing passenger rail system. Instead, he helped to boost its federal allotment this year to $1.3 billion. (Bush had pushed for just $800 million.)

“Better roads, bridges, airports, commuter rail systems, and other public transit options are needed to connect people to educational centers, health and social services, and, perhaps most importantly, good jobs,” he said in a January 2007 statement after being named an Appropriations cardinal.

Olver also used his seat to protect subsidized housing funding last year, boosting funds for Section 8 housing vouchers by $616 million more than Bush had requested and maintaining funds for the HOPE VI program, which helps communities build new mixed-income housing projects.

“Some members look at things from a national perspective. Olver really seems comfortable engaging in communities like Pittsfield and understanding how he can make the lives of people better,” says Pittsfield Mayor James Ruberto. “He puts tremendous emphasis on being our representative in Washington. He’s more interested in helping us than enlarging his profile.”

That would seem to be an understatement. During 17 years in Congress, Olver has sponsored about 40 bills and only two of them, both minor initiatives in his home district, have gone on to become laws. His voice is rarely heard on issues of national import.

His website, unlike those of higher profile colleagues, such as Rep. Ed Markey of Malden or Rep. Barney Frank of Newton, is almost completely lacking any commentary on big national issues in favor of the strictly parochial. Recent offerings, for example, tout a House bill he’s introduced recognizing Pittsfield as the birthplace of college baseball, and passage of another bill he sponsored to designate the Monadnock, Metacoment, and Mattabesett Trail System in central Massachusetts a “National Scenic Trail,” thereby winning National Park Service funding for its maintenance.

That lack of flashiness would square with Olver’s personality. His office space is colorless by congressional standards, with a few framed newspaper clippings from back in the district, an award from a rail passenger group, and some posters of the national parks.

“He’s not an exciting, dynamic guy,” says Sullivan. “He just gets the job done. He’s a professor. He has that professorial look and feel to him, and when he moves up to the podium to give an address, we know we’re in for a lesson.”

Fit and trim at 71, the six-foot-four-inch Olver freely admits that he prefers to hit the trails or go rock climbing rather than hobnob at Washington soirees. (He once called one such event a “foolish show.”) Olver cultivates so well the image of the rural New England professor that some are surprised to learn he’s not actually a native of the area, having grown up on a farm in the Poconos area of Pennsylvania.

Always a cerebral type, Olver recalls sitting for hours during elementary school flipping through an encyclopedia. He graduated from high school at 15, got his bachelor’s degree from Rensselaer Polytechnic Institute in upstate New York when he was 18, and got his doctorate from MIT at 24. He was a chemistry professor at UMass–Amherst before winning a seat in the Massachusetts House at age 32.

He says his interest in politics began during a sabbatical from teaching when he found himself spending more time perusing The New York Times than the scientific journals he was supposed to be reading for work. His first foray into politics came in 1968 when he won the state House race. In 1972, he beat an incumbent Republican to join the state Senate, where he remained until 1991. That year, he won a 10-person Democratic primary to run in a special election to replace longtime Republican Rep. Silvio Conte, who had died in office that February. Olver’s victory in the general election marked the first time since 1892 that the district elected a Democrat.

Olver’s politics are down-the-line liberal. He has said that global climate change is the issue of the century — it’s one of the very few big issues where he’s an outspoken advocate — and has pushed unsuccessfully for legislation to cap carbon dioxide emissions from the burning of fossil fuels. He opposed the Iraq war from the start and, with Rep. Jim McGovern of Worcester, sponsored a measure last year mandating the withdrawal of US troops within six months. And he feels strongly about human rights issues. In 2006, he was arrested at a rally outside the Sudanese Embassy in Washington, organized by McGovern, to protest that nation’s civil rights abuses.

“Civil disobedience is a tough enough thing to do for people who are not elected,” says McGovern. “But John came without hesitation. He realizes that some things are so awful and so outrageous they demand we take action.”

At times, his passions can get the better of him. Last year, Olver reportedly told liberal activists — when challenged about his refusal to endorse an impeachment resolution against Vice President Dick Cheney — that he believed the Bush administration might attack Iran and then use criticism of the attack as a pretext for canceling this fall’s presidential election. Olver later clarified, through a spokesman, that he didn’t mean his comments as a prediction.

Olver can also be something of a puzzle to liberals in his district, who note that he owned oil company stocks at the same time that he chaired the House Climate Change Caucus and has been more reliant than many of his colleagues, both in Massachusetts and in the House, on donations from corporate and union political action committees.

In February, Stockbridge lawyer Robert Feuer launched a Democratic primary challenge to Olver to protest his refusal to support the impeachment resolution. “I think the type of political analysis that he made on that resolution shows how he’s failed in his duty to the voters,” says Feuer, who filed in June more than 2,500 signatures to get on the September primary ballot.

But Olver’s refusal to go along with the far left indicates that he can be a practical politician, too. In a reflective moment, he explained that his opposition to the impeachment resolution wasn’t out of any sympathy for Cheney, but rather out of concern that it would play poorly in this year’s presidential race and hurt Democratic efforts to defund the Iraq war by alienating congressional Republicans.

Olver may need all the political acumen he can muster if, as seems inevitable, Massachusetts loses one of its 10 House seats after the 2010 Census. As the eldest of the Bay State House members, with a district whose growth has been slower than its eastern counterparts, rumor has it that Olver will be the one to go. Olver, who was reelected to an 8th full term two years ago (getting 76 percent of the vote against an independent candidate but unopposed by Republicans), won’t speculate on what the future will bring. For the time being, he promises to remain Massachusetts’s money man in Washington.