I thought that when I heard the president's remembrance of Holbrooke on Monday: "As anyone who has ever worked with him knows - or had the clear disadvantage of negotiating across the table from him - Richard is relentless.
"He never stops. He never quits. Because he's always believed that if we stay focused, if we act on our mutual interests, that progress is possible. Wars can end. Peace can be forged."
Throughout more than four decades of public service, Specter has embodied many of the same characteristics. He was elected D.A. in the Republican no-fly zone of Philadelphia. Became a hard-charging prosecutor battling corruption. Helped investigate the Kennedy assassination on the Warren Commission.
He lost elections for mayor of Philadelphia, the Senate and governor before finally winning his Senate seat in 1980. For three decades, he staked out the political common ground as the Senate became increasingly overwhelmed by polarization and gridlock.
He beat open-heart surgery, a brain tumor and Hodgkin's disease (twice).
In short, he defied any number of odds to become not only Pennsylvania's longest-serving U.S. senator, but also one of the most influential elected officials in the country.
His legacy as such will likely revolve around his accomplishments in the realm of the judiciary. As longtime Pennsylvania political observers Terry Madonna and Michael Young noted this week, Specter played a significant role in the confirmation of 14 Supreme Court justices and at least 125 federal trial and appellate judges during his stay on the Judiciary Committee.
Others will cite his investigative prowess. From the Warren Commission and the single bullet "conclusion" (as Specter insists upon putting it) to Spygate and the New England Patriots, Specter never shied away from a good inquiry.