Scott Brown's Campaign Against Both Warren and GOP Establishment

May depend on drawing in Obama-voting independents

This Thursday brings the first debate of Massachusetts's blockbuster US Senate campaign. But the real showdown that will decide the contest is not between incumbent Scott Brown and challenger Elizabeth Warren, but between Brown and the Republican Party.

Now that summer's over and the sprint is on to the November 6 election, polls and most close observers agree on where the race stands: each candidate has a solid 45 percent of the vote tucked away, and they pretty much cancel each other out. Brown has a slight lead, but that should be negated by Warren's expected turnout advantage.

This leaves the race in the hands of the middle 10 percent, or some 300,000 persuadable voters statewide.