Our choice for the US Senate will say more about us than it will about John Kerry or Bill Weld.

It will tell us whether we think that seriousness of purpose is a character flaw; it will say whether we believe that self-interest overrides the social compact that historically has bound have and have-not in one commonweal.

In 10 days, we will decide who we are.

We are all susceptible to a political personality with the easy confidence of a William Weld. He's the kid brother coaxing us out to play, waving away our protests about the homework we have yet to do.

He waves away our grownup concerns too -- about how we'll pay for our children's educations, how we'll care for our aging parents -- all smiles and reassurance that there is no issue that will not yield to his winning ways.

He tells us what we want to hear and we listen, ignoring a lifetime of experience that cautions us against the simplistic solution. With demanding lives to live, we are tempted to think we can lay the public burden down.

But what is the political, after all, but the personal writ large?

This election is not about which of two wealthy men is more like the rest of us. The answer, clearly, is neither. It's about which one has invested the time and energy to understand the kinds of challenges he will never have to experience firsthand.

By that measure, our choice could not be clearer.

For 12 years, John Kerry has stood with working people, with the unemployed, with the most vulnerable among us who at one time or another needed the assistance of a government for which Bill Weld has only a breezy contempt.

When he focuses on his job long enough to confront an issue, Weld's prescription is invariably punitive, never preventive.

We can't keep our kids away from drugs and out of gangs just by putting them in jail. John Kerry fought GOP attempts to slash $200 million from the Safe & Drug Free Schools Program; he wrote the law that created YouthBuild, a job-training and education program for kids at risk that Weld's GOP friends in the Senate tried to eliminate last year.

We can't give wage earners economic opportunity by directing tax cuts to the richest among us, as Weld has in Massachusetts. John Kerry voted to raise the minimum wage to $5.15 an hour -- a paltry sum that Weld insists this economy cannot afford.

We can't give all students an equal shot at higher education by vetoing $22 million in student scholarship funds, as Weld did in Massachusetts. John Kerry has been a consistent vote for aid to students who were not signed up for Harvard or Yale at birth.

We can't keep working people from slipping into poverty by vetoing unemployment insurance for workers locked out of their jobs, as Weld did with the ComGas workers. John Kerry wrote the law permitting the unemployed to borrow without penalty from their IRAs.

Those aren't personality differences.

Kerry may be earnest, but he's also engaged. By contrast consider Weld's record, a level of disengagement that would have gotten a corporate chief executive fired, not promoted.

He's in charge of a Department of Social Services that he underfunds, understaffs and undermines by ignoring the voices warning of the perils to this state's neediest children; a Department of Industrial Accidents that hires a convicted drug smuggler and promotes a convicted wife beater; an educational empire run by men -- John Silber and Bill Bulger -- once denounced by the governor as "an intellectual bully" and an "old-style pol."

John Kerry is not without flaws. He made some ill-considered housing choices a decade ago that I wish he hadn't. But he broke no law. He fell into the trap too many politicians do: assuming that the voters' trust can be taken lightly.

But Weld is no less vulnerable to the charge that he is a rich man isolated in a social world dominated by other rich men.

It may be a conceit for a rich man to empathize with a poor one, but it is sin to disdain him. Kerry has made a career of trying to bridge the gap. Weld has made a career exploiting our basest resentments of the poor, the addicted and the vulnerable.

The other day, as the campaign sank deeper into the muck, Weld told radio personality Don Imus that "this race is just beginning to tickle my funny bone. I'm having fun, fun, fun."

Our choice in 10 days is between a man who will entertain us and a man who will take us and the job at hand seriously.