In the shadow of the Rocky Mountains, many in wheelchairs, many who had lost loved ones to disease, and many who knew a cure wouldn't come in time for them but could save others wanted leadership that fought for them back in Washington. I have not forgotten the looks in their eyes, or my promise to them.

That's why I was stunned that the president's political adviser, Karl Rove, chose Denver to announce that President Bush is threatening to use the veto pen for the first time in his presidency to strike down a stem-cell research bill that offers hope to millions of Americans suffering from devastating illnesses.

President Bush has signed 1,163 bills into law without vetoing a single one of them. A veto now would send a message to all Americans that, on crucial issues, our differences are greater than our shared convictions. It would tell the world that America no longer wants to be the country that pushes the envelope of scientific knowledge and discovery.

Congress has taken the politics out of stem-cell research. It's time the White House does, too.

What a tragedy it would be if the first veto of Bush's presidency were used to make a political wedge of something that Washington and the rest of America overwhelmingly support - regardless of their political party - and a promise that offers hope to millions and could put American on the path to leading the world in the discovery of cures.

The issue of stem-cell research is deeply personal and raises profound moral questions. But people of goodwill and good sense can resolve these complex ethical issues without stopping lifesaving research. The House of Representatives has passed bipartisan legislation led by Rep. Diana DeGette, and the Senate is poised to pass groundbreaking stem-cell legislation in the next few weeks, with the support of Republicans like John McCain, R-Ariz., Bill Frist, R-Tenn., Orrin Hatch, R-Utah, and Nancy Reagan.

Growing numbers of conservatives have looked at the scientific facts and searched their own consciences in realizing that opposing this groundbreaking research isn't a 'pro-life policy,' that an ethical consensus can be found to ban human cloning while protecting stem-cell research.

The stakes couldn't be higher. More than 100 million Americans suffer from illnesses that might one day be cured away with stem- cell therapy. Stem cells could replace damaged heart cells or cells destroyed by cancer, offering a new lease on life to those with a diagnosis that once came with a death sentence. Research has the potential to slow the loss of a grandmother's memory, calm the hand of an uncle with Parkinson's, save a child from a lifetime of daily insulin shots or permanently lift a best friend from a wheelchair.

Some of the most pioneering cures and treatments are now right at our fingertips, but because of politics they could remain beyond reach. Every day we wait, more than 3,000 Americans die from diseases that may someday be treatable because of stem-cell research.

Americans have been presented with a false choice between the sanctity of human life and the scientific knowledge that can save it. The president's veto rests on the false assumption that we have to choose between our dreams and our principles. We can have both.

We can support our scientists, help the sick and ensure that our legal and ethical boundaries reflect our unshakable sense of human dignity.

I'll never forget a woman I met at a town hall meeting on stem- cell research. She stood up, her frail body shaking, and pleaded for her government to embrace stem-cell research. It was the moral clarity of her message that will stay with me forever. 'It's too late for me,' she said, 'but we need to do this for those who still have hope.' It's not too late for this President to change his mind before tying the hands of doctors and ethicists with a veto. It's not too late to give millions of Americans what they want most of all: hope.

John Kerry is a U.S. senator from Massachusetts and was the 2004 Democratic presidential nominee.