A new automated poll out Tuesday found Rep. Edward J. Markey, D-Mass., with a 12-point lead over Republican Gabriel Gomez in the upcoming Senate special election.

Markey took 52 percent in the New England College poll, with 40 percent backing Gomez and 8 percent undecided. Both candidates received the support of about three-quarters of voters in their own party, which — given the state’s severe Democratic lean — gave Markey a big edge over Gomez.

The poll arrived as both campaigns launched new TV ad campaigns this week. Just three weeks remain before the June 25 race to fill the remaining Senate term of Secretary of State John Kerry.

It’s Markey’s race to lose, but Democrats are not taking it for granted — especially after watching Republican Scott P. Brown win the seat of the late Edward M. Kennedy in a 2010 special.

Internal polling in the past month showed Gomez within single digits of Markey, an encouraging sign for Republicans who hope to add a seat to their column for the rest of this Congress. His goal is to win close to 60 percent of independent voters, who make up about half the total electorate in the Bay State.

National Republicans have sent staff and encouraged donors to ante up for Gomez, who started the race at a sizable fundraising disadvantage. At the same time, Gomez has attempted to highlight his independence from the national party line on issues such as gay marriage, gun control and climate change.

The poll of 734 registered voters who said they plan to vote in the special was conducted June 1-2 and included a 4-point margin of error.

Rothenberg Political Report/Roll Call rates this race Democrat Favored.