MARGARET WARNER: When Massachusetts Senator Edward Kennedy died last August, it was taken for granted that the seat he had held for decades would be filled by another Democrat. Family friend Paul Kirk became interim senator, until a special election could fill the seat for real.
The Democratic candidate in Tuesday's election is state attorney general Martha Coakley. A lifelong prosecutor, she's decidedly unflashy.
SCOTT BROWN: Hi, guys.
MARGARET WARNER: Her opponent is state Senator Scott Brown, who, at 22, posed for a nude centerfold in "Cosmopolitan" magazine. Calling himself an independent conservative, he has vowed, if elected, to provide the 41st vote to block the Democrats' health care reform bill in the Senate.
From the outset, Coakley wrapped herself in the Kennedy mantle, and early polls showed her with a 30-point lead.
MARTHA COAKLEY: As some have noted, no one can fill his shoes, but we must strive to follow in his footsteps.
MARGARET WARNER: But, in recent weeks, Brown has surged. A turning point came just after Christmas, when Brown aired an ad comparing himself to President John F. Kennedy.
JOHN F. KENNEDY: ... will have both immediate and permanent benefits to our economy.
SCOTT BROWN: Every dollar released from taxation that is spent or invested will help create a new job and a new salary.
MARGARET WARNER: Coakley did not respond, and, in early January, polls showed the race tightening. With a filibuster-proof Senate majority at stake, Democrats belatedly began pouring talent and ad money into Coakley's campaign.
NARRATOR: He drives around in a pickup truck, but you have got to look under the hood to find the real Scott Brown. On health care, Brown wants to be the deciding vote to kill Ted Kennedy's legislation.
MARGARET WARNER: But Brown appeared to get another boost from Monday night's debate with Coakley and third-party candidate Joe Kennedy, no relation to the late senator. Coakley painted Brown as a conservative in the mold of George W. Bush.
MARTHA COAKLEY: He wants to go back to the drawing board. He does indeed. He wants to go back to those Bush/Cheney policies that provide for the very wealthiest.
MARGARET WARNER: Brown painted Coakley as a liberal rubber-stamp for President Obama.
SCOTT BROWN: You're in favor of cap and trade, which is a national energy tax. You've said...
MARTHA COAKLEY: It's not a tax.
SCOTT BROWN: It's a tax.
MARTHA COAKLEY: It's not a tax.
SCOTT BROWN: You're in favor of a health care bill that's going to be about a trillion dollars.
MARGARET WARNER: Moderator David Gergen asked Brown if he would use -- quote -- "Ted Kennedy's seat" to block health care legislation that Kennedy had championed.
SCOTT BROWN: With all due respect, it is not the Kennedy seat, and it's not the Democrats' seat. It's the people's seat.
MARGARET WARNER: In the closing days, senior Massachusetts Senator John Kerry has e-mailed supporters for donations to Coakley's campaign. And President Obama recorded an Internet video on her behalf.
U.S. PRESIDENT BARACK OBAMA: As your attorney general, Martha has taken on Wall Street schemes, insurance company abuses, and big polluters on your behalf. She represents the best progressive values of Massachusetts.
MARGARET WARNER: Today, Ted Kennedy's widow, Vicki, added her voice.
VICKI KENNEDY: It's the people's seat, the mother struggling to make ends meet, the father trying to find a job. My husband fought for them, and so does Martha Coakley.
MARGARET WARNER: Brown's campaign has been active on the Web, too, with ads and vigorous fund-raising. Though a Boston Globe poll last Sunday had Coakley up by 15 points, a Suffolk University survey last night showed Brown with a four-point lead.
One further wild card, with implications for the health care vote, the Massachusetts secretary of state says it will take 10 days or more to certify the results of the election.