WASHINGTON -- A new poll on the Massachusetts Senate race confirms what other recent surveys have shown, at least collectively. The race between Republican Sen. Scott Brown and Democratic challenger Elizabeth Warren is close and likely to stay that way for the duration of the campaign.

Seen separately, however, the same polls paint an inconsistent picture, yielding everything from a 5 percentage point Warren advantage to a 9 percentage point Brown lead. While that variation's sources are difficult to pinpoint, it is likely to persist since poll methodologies differ widely and because many Massachusetts voters have not fully engaged in the race and are still weighing their choices.

The most recent automated telephone survey, conducted on April 9 by Rasmussen Reports, shows the two candidates "running neck-and-neck," with Warren at 46 percent and Brown at 45 percent.

That very close result is similar to the current estimate produced by the HuffPost Pollster chart, based on all public polls measuring voter preferences in the Massachusetts Senate race, shown below. The chart's trend lines currently give Brown an edge of just under two percentage points (44.6 to 42.7 percent)...