WHEN Pennsylvania's senior senator, Arlen Specter, exits the national stage early next month and rides off into the sunset, he'll do so as perhaps the most significant force in the history of Keystone State politics.

Specter has been Pennsylvania's leading advocate and cheerleader from the time of his first election to the Senate in 1980 to his defeat in the 2010 Democratic primary, always seeking ways for making the commonwealth better, stronger and more competitive.

An astute biographer could easily compile reams of pages about Specter's career, which began with his election as Philadelphia district attorney in 1965 and included being defeated for mayor in 1967, losing to John Heinz in the 1976 U.S. Senate primary, and falling to Dick Thornburg in the 1978 Republican gubernatorial primary.

He then went on to win 10 statewide primary and general elections for the Senate in subsequent years. Two particular attributes of Specter's long career represent his true legacy: an unwavering commitment to high-quality public service and his political centrism that allowed him to bridge the partisan divide at home and in Washington.

THE FIRST and perhaps most essential element of the Specter legacy is that he provided equal treatment for every Pennsylvania citizen, showed equal concern for each of the state's 67 counties and considered the importance of every citizen's views regardless of his political party identification.

While former President Calvin Coolidge once told a dinner party guest that his hobby was "holding office," Specter took public service more seriously than any elected official I have ever met and his record of successful constituent service and delivering for each county over his career reflects this.

When I first arrived at Specter's Capitol Hill office to work as an intern in September 2001 - a position I pursued at the urging of former Specter assistant district attorney and later state Sen. Bob Rovner - I quickly gained the impression that I was in an office that put people ahead of politics.

The entire group of incoming interns were told quite clearly that we were there to serve all Pennsylvanians and to delicately handle every interest and concern brought forward by all Pennsylvanians with inquiries.

The farmer in Crawford County struggling with a local agricultural issue was just as important to Specter and his team as the high-powered attorney in Philadelphia capable of writing a large campaign check.

The Democratic union member calling Specter's office for constituent assistance was likely to receive the same efficient and responsive service as the Republican businessman. Specter's operation was a shining example of democratic principles on display in a system of democratic governance.

Second, Specter's ability to bridge the partisan divide and ignore the ideological combat that consumes American politics today made him a true rarity in public life.

In his March 1995 announcement speech for his very short-lived presidential campaign, Specter asserted that the country as a whole suffers when ideological battles between the "intolerant right" and the "incompetent left" work to snuff out compromise, moderation and inclusion.

His self-described fiscal conservatism and social libertarianism provided an opportunity to appeal to a very broad cross-section of Pennsylvanians who understood the importance of sending a moderate, centrist senator to Washington to successfully represent the interests of the nation's most moderate, centrist state.

Pennsylvania voters overwhelmingly responded to Specter's pragmatic approach, which combined quality service to constituents and responsiveness on policy issues.

Over the course of his five Senate general election victories from 1980 to 2004, Specter accumulated almost 11.2 million votes. Within those five general elections, he also won an average of 57 of 67 counties - impressively taking 61 counties in 1986, 65 in 1998 and 63 in 2004, all while his party was in the electoral minority.

While Specter's departure from the Senate allows for an opportune time to celebrate his career and honor the legacy of possibly the most important senator in the history of Pennsylvania, his retirement should be viewed as bittersweet.

The commonwealth that he served so admirably is facing the loss of one or two House seats during next year's reapportionment. The state's congressional clout will be diminished with the death of Rep. Jack Murtha and the defeat of Rep. Paul Kanjorski earlier this year.

Meanwhile, the state's economy is stagnant and there will be no U.S. senator with any significant seniority to guide tax dollars and federal projects back home, as Specter did for decades.

While we should collectively thank Specter and wish him and his family well in retirement, it seems as if now is the time when Pennsylvania needs him most.

Let's hope for the good of the commonwealth - and the nation - that whoever attempts to fill his shoes in the future practices the same brand of pragmatic, consistent, patriotic politics that Specter has throughout his long and storied career.

Nathan R. Shrader is a Ph.D. student in Temple University's Department of Political Science and a Republican committeeman in Philadelphia.

He can be reached at NRS@Temple.edu.