Why Kerry? Because he's rich enough (or at least his wife is that wealthy) to self-fund his 2004 Presidential campaign... The Democrats are currently 90% short of their 527 fundraising targets for 2004.
They are losing their House races. They are losing up to 5 Senate seats, and they can't afford to run a decent Presidential campaign.
But if they nominate Kerry, then his wife gets stuck with the bill.