The former Vermont governor and the Missouri congressman each drew the support of 26 percent of Iowa Democratic voters surveyed, while Sen. John Kerry (search) of Massachusetts had 15 percent, according to the poll released by KCCI-TV.
Eighteen percent of those questioned were undecided. The remaining candidates were in single digits.
The telephone survey of 400 registered Iowa Democrats who said they were likely to vote in the Jan. 19 precinct caucuses was conducted Oct. 26-28 by the polling firm Research 2000 (search).
The margin of error was plus or minus 4 percentage points.
Dean and Gephardt were about even in a similar Research 2000 poll in August, while Kerry's support was unchanged.
Connecticut Sen. Joe Lieberman (search), who had 12 percent support in the August poll, slipped into the single digits after announcing he would bypass the Iowa caucuses.
In a separate sample, Research 2000 questioned 600 registered Iowa voters, including Republicans and independents, about their preferences between each Democratic candidate and President Bush.
In a matchup with an unnamed Democrat, 46 percent of respondents picked Bush, while 47 percent picked the unnamed Democrat.
In August, Bush held a slight lead.
That survey was taken during the same period as the Democratic poll and had a margin of error of plus or minus 5 percentage points.