When a little known Republican state senator beat Massachusetts' Democratic attorney general in a 2010 special election, it rocked the political world. Scott Brown, a onetime model who had driven across the state in a pickup truck, ended the Democrats' brief filibuster-proof 60-seat Senate majority, throwing into doubt the passage of ObamaCare. Nearly three years later, Democrats want Ted Kennedy's former seat back, in one of the closest-fought races of the 2012 election. Here's what you should know:


Sen. Scott Brown (R)
First-term incumbent; won a special election in January 2010 to fill out the term of the late Sen. Ted Kennedy (D)
Age: 53

Elizabeth Warren (D)
Harvard Law professor and the creator of President Obama's Consumer Financial Protection Bureau
Age: 63

At the beginning of their race, Brown and Warren agreed to run a civil campaign and signed a "People's Pledge" to actively discourage outside groups, mostly super PACs, from running ads on their behalf. The outside-spending pledge is mostly intact, but the tenor of the race is getting increasingly negative. Brown is hitting Warren over her disputed claim to be part Cherokee and Delaware Indian, and for doing legal work for big corporate clients — a history he claims undermines her image as an advocate for the little guy. Meanwhile, Warren is hammering Brown's voting record in the Senate and fealty to the Republican Party, which her side believes undermines his claim to be an independent vote for the largely Democratic Bay State.

Warren: 46.8 percent
Brown: 45 percent
(See the full data here.)

CASH ON HAND (as of Aug. 17): 
Brown: $14.2 million on hand; $19.5 million total 
Warren: $12.3 million on hand; $28.3 million total


Scott Brown: "On Your Side"


Elizabeth Warren: "Too often"

Read more political coverage at The Week's 2012 Election Center.