Former Vice President Joseph R. Biden is the strongest Democratic contender for the Iowa caucuses, according to a poll of likely caucusgoers.
A survey from Emerson College showed that Mr. Biden, with 29 percent, had a double-digit lead over Sen. Kamala D. Harris, a California Democrat who launched her campaign just weeks ago.
Although expected to be a front-runner, Mr. Biden hasn’t announced whether or not he’ll be running, but he’s hinted over the past month that a decision could be coming soon.
In December, Mr. Biden said he was the “most qualified person in the country to be president.”
Rounding out the leader’s pack was Sen. Bernard Sanders, Vermont independent, with 15 percent, followed by Sen. Elizabeth Warren, Massachusetts Democrat, with 11 percent of the vote.
Ms. Warren launched her exploratory committee in December, but Mr. Sanders has not made an announcement about his plans for 2020.
None of the other declared candidates garnered more than 5 percent.
In the data, Mr. Biden is also the only Democrat who was able to edge out President Trump, winning Iowa’s support 51 percent to 49 percent.
Mr. Trump beat the rest of the poll’s Democratic front-runners. He had small margins of victory over Ms. Harris — 53 percent to 47 percent — and Ms. Warren — 52 percent to 48 percent. However, he barely pulled ahead of Mr. Sanders, splitting the voters 51-50.
The poll surveyed 260 likely Iowa caucusgoers from Jan. 30 to Feb. 2 and had a 6 percentage point margin of error.