During his 45 plus years in the U.S. Senate, Ted Kennedy has been the exemplar of what it means to be a progressive Democrat. Decade after decade, he has led on issue after issue--from improving America's health care, towards expanding votings rights, raising the minimum wage,unwise wars in Iraq and Vietnam, improving the rights of workers, opposing the judicial nominations of right-wing extremists. His record has been so good for so long that many progressive groups in Washington reliably use Ted Kennedy's positions as the exemplar of what a responsible progressive position on a given issue is.

More than any other U.S. Senator, he has a national constituency. He ran a strong race for the Presidency in 1980 against Jimmy Carter in the Democratic primaries, and made a widely heralded speech at the 1980 Democratic National Convention about "the dream that will not die." Had it not been for unwise, unfortunate, and tragic personal life decisions aggravated by the weight of exposes about his late father and martyred brothers, he probably would have become one of our great Presidents.

One of his biographers, Burton Hersch, said that his Senate career was so influential on so many areas of public policy that it amounted to a "shadow Presidency." 27 of his 45 years in the Senate have occurred during Republican Presidencies, and the Democratic Presidencies of Jimmy Carter and Bill Clinton, hampered by internal and systemic Democratic weaknesses, were far less ambitious than the Presidencies of John Kennedy and Lyndon Johnson under which his career began.

So Ted Kennedy has long been the voice of those who long for a Presidency aggressively and successful dealing with major national challenges, those who think that the best strategy for a better country is to actively promote traditional Democratic goals rather than to finesse Republican goals. It is unlikely that a Ted Kennedy presidency would have emphasized wearing sweaters to fight energy dependency as President Carter did, or issues such as school uniforms and V-Chip parental television controls as President Clinton did.

Because there is large constituency--of which I am one--that has felt its concerns having too little weight in the White House regardless of who has been President, Ted Kennedy has been a beacon of hope for two generations now. The year Jimmy Carter was elected, polls showed non-candidate Ted Kennedy as the choice of most Democrats. Ted Kennedy's passionate and aggressive support for Michael Dukakis in 1988 and John Kerry in 2004 was an essential component of their primary successes. His more low-key support for Paul Tsongas in 1992 helped him win a number of primaries against Bill Clinton.

Barack Obama is the first candidate Ted Kennedy has backed for the Democratic Presidential nomination who is not from Massachusetts, a state he and President Kennedy helped convert to a Democratic stronghold from its prior status as a Republican stronghold outside of the Boston area. Kennedy's aggressive campaigning for those he backs makes clear that he understands that endorsements have to persuade in order to be effective.

In Iowa in 2004, John Kerry had Ted Kennedy while his rivals had almost every politically active union and the vast majority of the campaign volunteers and the vast majority of total dollars spent. The credibility that Ted Kennedy's support gave Kerry helped him overcome both early front-runner Dick Gephardt and late front-runner Howard Dean.

The most important endorsements in primaries are from voters in other states. After that, the most important endorsement a Democratic candidate can get is Ted Kennedy's.

Barack Obama, in my judgment, is now at least the slightly favored front-runner for the Democratic Presidential nomination because of it.