By Noah Bierman Globe Staff

US Representative Edward Markey leads Representative Stephen Lynch by 7 percentage points in a new poll, a clear margin but perhaps not as wide as some political insiders would have predicted in the Democratic primary to succeed John Kerry in the US Senate.

The WBUR/MassInc telephone poll of 498 registered voters taken Monday through Wednesday shows Markey, of Malden, leading Lynch, of South Boston, 38 percentage points to 31 percentage points among voters who said they were likely to vote in a Democratic primary, just inside the margin of error of plus or minus 4.4 percent.

The poll shows Lynch with a slightly stronger favorability rating. Both candidates were viewed favorably by 29 percent of poll respondents. But more voters had an unfavorable opinion of Markey than Lynch – 19 percent compared with 12 percent. About a quarter of those surveyed had never heard of either congressman.

The Republican field of potential candidates remains in flux, but the poll suggests Democrats retain their strong advantage in the race, with better name recognition for their candidates and overall preference from voters for left-leaning contestants. The poll showed 48 percent of voters more likely to pick a generic Democrat in the race compared with 26 percent likely to vote Republican, a finding in keeping with the state’s propensity to elect Democrats to federal office.