President Lyndon Johnson signed Medicare and Medicaid into law in the Truman Presidential Library in Independence, Missouri. The law took effect almost a year later – 45 years ago this week – on July 1st, 1966.

At the time that Medicare took effect, only half of Americans 65 and older had access to health care coverage. A third of American seniors lived in poverty.

“Poverty was so common that we didn't know it had a name,” Johnson said, describing a time before Medicare.

Today, virtually every American over 65 has access to health care. And the number of seniors that live below the poverty line has dropped by 75 percent.

That’s no accident. Medicare provides 47 million Americans with the access to care and the protection from poverty that Truman envisioned more than 65 years ago.

And Medicare and Medicaid don’t only protect seniors from poverty – they also protect those seniors’ children. Forty-six years ago, middle-class families often spent themselves into the poor house honoring their commitment to their fathers and mothers. Today seniors and their children have the security that Medicare and Medicaid will be there to honor that commitment – providing health care and nursing home care when they need it.

But Medicare doesn’t only save American seniors money. It also saves their lives.

In 1964, just before Medicare was signed into law, seniors lived an average 70 years. Today, the national average is more than 78 years. There is, perhaps, no achievement greater than that. This law literally extended Americans’ life expectancy.

Forty-six years ago, before signing Medicare into law, President Johnson made this vow:

"No longer will this nation refuse the hand of justice to those who have given a lifetime of service and wisdom and labor to the progress of this progressive country."

Democrats intend to honor that solemn vow. But today Medicare is under siege.

Republicans would trade away the health and safety of today’s seniors for the sake of tax breaks for billionaires, wealthy oil companies and corporations that ship jobs overseas. They would trade that sense of security – that “hand of justice” Johnson described – to protect tax breaks on corporate jets.

Their ideological budget would end Medicare as we know it, once again subjecting seniors to the rising costs of health care. Democrats refuse to let that happen.

A lot has changed since 1966. New technologies have been developed that keep Americans healthier and help them live longer. New medicines for diabetes, Parkinson’s and Alzheimer’s are being invented all the time. And hip replacements and chemotherapy – pioneered in the 60’s – are now performed in the United States every single day. Medicine has changed.

But one thing hasn’t changed: seniors need Medicare. In fact, the rising cost of health care today means seniors need Medicare’s protection now more than ever.

That’s why I will never stop fighting to preserve this successful program. As long as I am in the Senate, I will oppose Republican plans to weaken or undermine it. Because Republicans’ plan to end Medicare is one idea whose time will never come.