The DSCC poll was in the field May 8-10, at the same time that the controversy over Warren's ancestry was garnering major local and national headlines.

Voters were split when asked whether developments in recent weeks made them more or less likely to vote for Warren, which Democrats are sure to use to argue the controversy has been a media creation with little effect on the race. But voters weren't asked about the controversy specifically. Instead, pollsters asked generally about "things you've seen or heard about Elizabeth WarrenElizabeth Ann WarrenFix the flaw in financial self-regulation Power struggle threatens to sink bank legislation Feinstein faces new pressure from left over CIA nominee MORE in the past few weeks."

An independent poll of the Senate race by Suffolk University is scheduled to be released on Wednesday.

The DSCC poll of 502 likely voters was conducted using live telephone interviews and had a margin of error of plus or minus 4.4 percentage points.

The Hill rates this race a toss-up.