There is a map of the United States’ congressional districts on RealClearPolitics.com, coloring them in varying shades of red or blue that correspond with the likelihood of either party claiming them in this year’s midterm elections. The map, naturally, does not name the candidates in each race; the colors are enough.

Caught up in the battles for the House and Senate, it becomes easy to view each legislator as little more than a tally toward their party’s vote total; not an entirely unfair assumption to make, considering the well-publicized partisan divisions that have brought Washington to a standstill. Despite this apparent homogeneity, however, some legislators still stand out by passionately supporting elements of both party platforms or developing irreplaceable areas of expertise.

Minnesota Democrat Jim Oberstar, who died this month on May 3, did both. The longest-serving congressman in state history, Oberstar represented the 8th district for eighteen consecutive terms before being upset by Tea Party favorite Chip Cravaack in 2011. Best known as the head of the Transportation Committee, he attracted millions of dollars in earmarked funding to highway and bridge projects to his home state.

While scoring big in pork-barrel spending isn’t generally a sign of political integrity, these initiatives underlined Oberstar’s lifelong commitment to improving the nation’s transportation industry. He saw infrastructure investments as both long-term assets and short-term job creation opportunities. Oberstar also became a leading advocate for the development of intermodal transportation—connecting highways, airports, and rail lines with public transit services.  His Washington Post obituary called him a “serious and hard-nosed expert in public works and transportation issues.”By devoting himself to infrastructure development, Oberstar built a continuous—and universally useful— body of work.

Oberstar was also notable for his firm adherence to a set of principles that transcended party lines. A sincere Catholic, he maintained a progressive economic agenda while staying true to the Church’s doctrines on most social issues. Perfectly capturing the sort of populist orthodoxy typical of the Iron Range, Oberstar’s firm commitment to both fiscal liberalism and social conservatism built him a blue-collar coalition that endured for decades.

Just as his transportation earmarks were more than pork, however, Oberstar’s split loyalties were more than a political balancing act. Rather, he proved willing both to set himself against his own party and to provide ammunition to conservative opponents in defense of his views.  During his last term in Congress, Oberstar fought alongside Republicans to remove provisions allowing government funding for abortion from the Affordable Care Act. After that initiative succeeded, he went on to become one of the law’s most dedicated proponents, even as Obamacare became a rallying point for Cravaack in the 2010 election. For better or for worse, Oberstar remained faithful to his ideals.

Oberstar’s career illustrates two important lessons for his colleagues. First, unlike those who use a brief and unremarkable congressional career as a springboard for higher office, he was a public servant in the truest sense of the phrase. He positioned himself not as a power broker, but as a specialist— and hundreds of transportation projects throughout the country bear the stamp of his expertise. Second, Oberstar embodied principled moderacy. He was not a moderate because his convictions were negotiable, but rather because he was unwilling to abandon parts of his worldview for his party’s sake.

Rather than diluting each other, his fiscal progressivism and social conservatism complemented one another to form a coherent philosophy—one rooted in respect for life and labor alike.