As Markey expands polling lead, Obama plans Boston fundraiser

In the survey, conducted by New England College, Markey takes 52 percent support to Gomez's 40 percent support. Eight percent of voters remain undecided.

But 22 percent of those polled say they're still unsure about Gomez. The National Republican Senatorial Committee released a web video on Tuesday introducing him to voters, but the online effort is unlikely to gain traction with many of thsoe voters.

Gomez has kept Markey's lead to single digits in most polls of the campaign, but this new poll may indicate that the heavy volley of attacks between the two candidates may be taking a toll on Gomez.

He's been forced by Democrats to answer for a controversial tax deduction he took on his home in 2005, as well as recent fundraising pitches sent by prominent Republicans characterizing his win as key to taking back GOP control of the Senate and obstructing President Obama's agenda.

The president remains popular in Massachusetts, and voters there are wary of the national GOP. Gomez has run as a "new kind of Republican" and pledged to buck his party when necessary, but fundraising pitches from the likes of Senate Minority Leader Mitch McConnellMitch McConnellSenate Dems: Add Flint aid to spending deal Zika funding fight throws wrench in health lobbyists’ plans Shutdown risk grows over Flint MORE (R-Ky.) and Sen. Marco RubioMarco RubioGlenn Beck: I was wrong about Ted Cruz Senate rivals gear up for debates Rubio: End of Obama's term could be 'most damaging yet' MORE (R-Fla.) have undermined that message to some extent.

Despite the double-digit lead, however, Democrats are taking no chances with their nominee. Last week, First Lady Michelle ObamaMichelle ObamaClinton: Trump started his political career 'based on this racist lie' Some tough debate questions for Clinton and Trump (really) Week ahead: Election hacks, Yahoo breach in the spotlight MORE appeared at a fundraiser for Markey in Boston, and President Obama will hold a fundraiser for Markey next week — something he did for Martha Coakley, the Democratic nominee that lost to Republican Scott Brown in the 2010 special.

Gomez said in a statement that Obama's planned fundraiser is evidence Markey's campaign is "failing."

“Congressman Markey’s dirty campaign is failing to offer anything but old, tired solutions. I'm not surprised that he has to ask the President to try and bail him out," he said.

"I respect the President, I'll be happy to work with when I believe he's right, and I'll oppose him when I think he's wrong.  I'm independent minded, just like the people of Massachusetts.”

The New England College poll was conducted from June 1-2 among 734 registered voters who plan to vote in the special, and has a plus or minus four percentage point margin of error.