Tommy Wells, whose campaign commissioned the poll, says it shows he is well positioned to win the April 1 primary. (Michael S. Williamson/The Washington Post)

A recent poll commissioned by the mayoral campaign of D.C. Council member Tommy Wells shows the electorate is closely split among four top potential candidates in next year’s Democratic mayoral primary, with a third of likely voters still undecided.

In a mock primary of four likely candidates, incumbent Mayor Vincent C. Gray (D) held a small lead over the three council members who have launched mayoral campaigns — Wells (D-Ward 6), Muriel Bowser (D-Ward 4) and Jack Evans (D-Ward 2). Twenty-one percent said they would vote for Gray or would lean toward Gray if the election were held today, while 17 percent opted for Bowser, 16 percent supported Wells and 13 percent supported Evans. Thirty-one percent remain undecided.

The survey results were detailed in a July 18 memo from Wells’s pollster, Lake Research Partners, that has been shared with potential campaign funders in recent weeks. After The Washington Post obtained the pollster’s memo, the Wells campaign responded to subsequent questions from the Post about the poll’s methodology and questionnaire.

The poll of 503 likely voters in the 2014 Democratic mayoral primary was conducted between June 27 and July 1 — before three additional candidates, Reta Jo LewisChristian Carter and Nestor Djonkam, entered the race. The sample included both landline and mobile phones and was drawn by matching telephone numbers to lists of registered voters. Overall results carry a margin of error of plus or minus 4.4 percentage points.

Lake Research Partners is a well-respected Democratic polling firm, but the Wells poll remains a candidate-sponsored survey, meaning it should be read with the general caveat that candidate polls tend to produce more desirable results for that candidate than others.

After the initial heat, surveyors read respondents brief statements about each candidate, making note of each campaign’s likely key messages, then asked them again how they would vote. In the “informed” heat, Wells pulled even with Gray at 21 percent. Bowser gained two points, while Gray and Evans did not see any gain in support.

With a federal investigation into his 2010 campaign ongoing, Gray has not announced whether he intends to seek reelection, though he has hinted he is interested in running for a second term.

Wells’s pollster suggests in the memo that Wells is “very well positioned” in the race, with an “ability to attract additional votes in disproportionate numbers,” while Gray’s room to grow is limited, noting that only 31 percent of voters rate his job performance as excellent or good, vs. 67 percent fair or poor. In the informed heat, Wells pulled ahead in some subgroups, including those most likely to vote in the April 1 primary, adding, that a “well-resourced campaign is, of course, imperative in order to capitalize on these advantages.”

The poll stands to help Wells combat the perception that he will unable to compete with Bowser’s fundraising prowess and citywide political appeal, as well as the notion that Wells will be unable to win should Evans, another white male, remain in the race. In campaign finance reports released last week, Wells was outraised by both Bowser and Evans, but he touted his higher number of donations as indicating strong grass-roots support.

Wells said Monday that he found the poll results “very encouraging.”

“I think it shows there’s not a clear front-runner,” he said. “Undecided leads, but undecided never wins, so I feel very good about the poll.”

Capital Insight polling analyst Scott Clement contributed to this report.