The WBUR survey was similar to a poll released last week by Public Policy Polling that showed Markey with only a four-point lead. It also could undercut a separate survey, released Wednesday by Suffolk University/7 News, that showed Markey with a commanding 52-35 percent lead.

Still, there was good news for Markey in the WBUR poll. When undecided voters leaning toward one candidate or the other were included, his lead expanded to a 46-38 percent advantage.

The survey also showed voters seemed unconcerned by Gomez's main line of attack: that Markey, who has been in Congress since the 1970s, is a career politician. Sixty-nine percent of those polled said Markey's lengthy service made no difference or made them more likely to vote for the Democrat. Still, 79 percent said Gomez having never held elected office made no difference or made them more likely to vote for him.

But the single-digit separation for the candidates is still promising news for Gomez ahead of next month's election. Moreover, in heavily Democratic Massachusetts, Gomez is not seen as remarkably partisan. Only 32 percent of those surveyed say his views are very or somewhat similar to the national Republican Party; 26 percent say they are very or somewhat different.

The WBUR survey was of 497 likely voters, and carried a margin of error of plus or minus 4.4 points.