"It's a great national service when we get legislators that love to legislate, not because we need more laws or bills, but how to accomplish certain public purposes, by working effectively with others, and on a bipartisan basis, and to stay with it," said Kennedy's longtime friend John Culver.
"He's always seen politics as the way grease is supplied to our system to make it work," said former Boston Globe reporter Tom Oliphant.
"This is the cause of my life," Kennedy said at an emotional speech at the Democratic National Convention in August 2008 while endorsing then-candidate Obama. He spoke of "new hope that we will break the old gridlock and guarantee that every American -- North, South, East, West, young, old -- will have decent, quality health care as a fundamental right and not a privilege."
Kennedy, a longtime chair of the Senate's Committee on Health, Education, Labor and Pensions, called for extending Medicare coverage to all Americans, medical coverage for the uninsured and modernizing health care systems by using new technologies to cut costs. He also proposed to implement a rule that would require every American to have some form of health insurance, a point which became one of the key points of contention between Democrats and Republicans.
"We'll negotiate with insurance companies to keep premiums and co-pays low and help you with your premiums if you can't afford them," Kennedy wrote in a column published in the Boston Globe in June to push support for his plan. "We're also hearing that some Americans want the choice of enrolling in a health insurance program backed by the government for the public good, not private profit -- so that option will be available, too."
Kennedy first called for a national health care system in 1966, when he proposed an amendment to the Economic Opportunity Act.
Kennedy, along with other senators, sponsored the Health Insurance Portability and Accountability Act (HIPAA) in 1996.
In 1997, he rallied for the State Children's Health Insurance Program (SCHIP) under which uninsured children from low-income families could get insurance.
Kennedy sponsored the Family Opportunity Act of 2006, allowing states to expand Medicaid coverage to children with special needs. That same year, he voted for expanding the enrollment period for Medicare, and would later support a bill that required pharmaceutical companies to negotiate prescription drug prices covered under the same plan.
After he was diagnosed with cancer in May 2008, Kennedy was sidelined in congressional debates on health care overhaul, but, on July 9, 2008, he made a dramatic return and one of his final appearances on the Senate floor. He arrived to applause and cast one of the 69 votes to break a Republican filibuster against a bill that blocked cuts in Medicare payments to doctors. Days later, then-President George W. Bush's attempt to veto the bill was overridden.
Even though he was not able to attend health care hearings on Capitol Hill because of his medical treatment Kennedy led efforts to create a sweeping overhaul of the health care bill in the Senate and to lobby the White House on new legislation. In his absence, Sen. Chris Dodd of Connecticut took the helm of the Senate Democrats' effort to create a health care bill.
"For four decades I have carried this cause -- from the floor of the United States Senate to every part of this country. It has never been merely a question of policy; it goes to the heart of my belief in a just society. Now the issue has more meaning for me -- and more urgency -- than ever before. But it's always been deeply personal, because the importance of health care has been a recurrent lesson throughout most of my 77 years," Kennedy wrote in a July Newsweek editorial he penned with longtime friend and speechwriter Robert Shrum.
Ted Kennedy's Legislative Achievements
Even though his presidential dreams were shattered when a controversial car accident -- in which he was the driver -- led to the death of a 28-year-old woman, Kennedy became an influential liberal voice in the Senate. But he was also known for his bipartisan work on legislation such as the No Child Left Behind Act of 2001.
"One of the things he's been extraordinarily skillful at is his ability to work across the aisle," Culver said. "It's remarkable with Ted Kennedy being recognized as such an intense partisan figure, but how effectively he can work with the other party in the Senate, and have their respect."
First elected to represent Massachusetts in the Senate at age 30, Kennedy's commitment to a liberal legislative agenda -- pushing bills on health care and labor laws -- made him a powerful force in the Democratic Party, especially during his primary battle with Jimmy Carter in 1980 and arguments against Bill Clinton's centrist leanings in the 1990s.
"In the four areas that Kennedy has dominated... health care, in education, civil rights, immigration," Boston Globe reporter Peter Canellos said. "He has fundamentally changed the relationship between the government and individuals in that arena."
Here's a closer look at some of the other issues Kennedy heralded:
Kennedy's brother, President John F. Kennedy, introduced the Civil Rights Bill in June of 1963, only months after Ted Kennedy joined the Senate in November 1962. During a speech, President Kennedy asked Congress to "enact legislation giving all Americans the right to be served in facilities which are open to the public -- hotels, restaurants, theaters, retail stores and similar establishments."
The bill that, after a struggle, eventually passed the House of Representatives Feb. 10, 1964, and met strong resistance in the Senate, remained on the floor for a 57-day filibuster. Though Ted Kennedy was still recovering from injuries he sustained in a devastating plane crash April 9, 1964, he gave an impassioned speech pleading with members of the Senate to end the filibuster of the Civil Rights Bill.
"My brother was the first president of the United States to state publicly that segregation was morally wrong," Kennedy said. "His heart and his soul are in this bill. If his life and death had a meaning, it was that we should not hate but love one another; we should use our powers not to create conditions of oppression that lead to violence, but conditions of freedom that lead to peace."
The bill was passed by the Senate several months later and signed into law by President Lyndon B. Johnson July 2, 1964.
In 1970, Kennedy supported the Voting Rights Act Extension, which essentially lowered the voting age to 18.
"He has a commitment not just to civil rights in any racial or other aspects, but in terms of the forgotten and the outcasts and the dispossessed, that's his instinct," said Frank Mankiewicz, press secretary for then-Sen. Robert F. Kennedy during the 1968 presidential campaign. "Whether it's the 18-year-old vote, or farm workers or ordinary sort of run of the mill civil rights legislation, women's rights, children, it's all there."
Kennedy also came out as a strong supporter of gay rights and women's issues.
"Kennedy is one of the earliest advocates for gay rights," Oliphant, the former Globe reporter, said.
A few instances of Kennedy advocating gay rights include his opposition to the Defense of Marriage Act and the constitutional ban on same-sex marriage, his efforts to gain funding for HIV/AIDS prevention and treatment programs and, most recently, his support for expanding hate crimes to include sexual orientation.
As late as 2007, Kennedy voted to re-introduce the Equal Rights Amendment and ensured access to and funding for contraception. He also supported what many hailed as a women's rights issue by voting against a proposal to end funding for women-owned businesses, among other measures.
Kennedy introduced the Americans With Disabilities Act in 1990. The bill was designed to prohibit employers from discriminating in job hiring and in the workplace against people who had a disability.
"The crowning achievement of these decades of progress was passage of the Americans With Disabilities Act of 1990, and its promise of a new and better life for every disabled citizen, in which their disabilities would no longer put an end to their dreams," Kennedy said on the 17th anniversary of the act in 2007. "The Americans With Disabilities Act was an extraordinary milestone in the pursuit of the American dream. Many disability and civil rights leaders in communities throughout the country worked long and hard and well to achieve it."
In 1978, Kennedy co-sponsored Civil Rights Commission Act Amendments, which expanded the jurisdiction of the Civil Rights Commission to protect people from discrimination on the basis of disability.
In 2001, the third-longest serving senator supported the No Child Left Behind Act, which was first proposed by then-President George W. Bush. The bipartisan bill made it a requirement for states that received federal funding to develop a standardized assessment test for students in certain grades.
Supporters of the bipartisan bill said it increased accountability, but critics argued against standardized testing, saying it is not a true test of a student's ability.
"This is a defining issue about the future of our nation and about the future of democracy, the future of liberty, and the future of the United States in leading the free world," Kennedy said of the bill on the Senate floor. "No piece of legislation will have a greater impact or influence on that."
Kennedy's support earned him a fair share of controversy, even within his own party.
"I want you to think about this, and I have to say, this was a train wreck that was not intended. No Child Left Behind was supported by George Bush and Sen. Ted Kennedy and everybody in between. Why? Because they didn't talk to enough teachers before they did that," Bill Clinton said of the act in 2008.
But despite the criticisms, some say Kennedy is likely to be remembered as one of the greatest Senators of his time.
"I think they're gonna say he is one of the greatest legislators, or most effective legislators -- if not the most effective legislator -- the Senate has ever seen," Boston Globe reporter and author Susan Milligan said. "And I don't think you could find a sitting senator right now, Democrat or Republican, who would disagree with that assessment."