So yes Romney only lost by twelve, but if you include the Green votes he lost by 18. In 2005 Charlie Shannon, Republican turned Democrat who had held the seat since 1990 died, there was a special election. State Rep. Patricia Jehlen won the Democratic Primary, and beat Republican Bill White 55-45. White ran a good margin ahead of Romney.
That's an interesting race to analogize here, and I mean that positively. I would say that Jehlen wasn't just a weak candidate, she was
hated by the old machine in Somerville which voted for Bill White as a protest. Conversely, Bill White wasn't that strong a candidate, he just enjoyed a solid reputation in Somerville and became the suitable vehicle for protest votes.
Differences: state vs. federal races, obviously. White was a liberal who differed from the city Democrats on local policies and has actually switched to the Democrats since that election. People didn't mind elected a Republican to the legislature, but might feel differently about sending George W. Bush another proxy in Washington. Secondly, I can't imagine people hate Niki Tsongas with the fervor they felt against Jehlen. Some people will want to vote against her because they don't respect her or how she won the nomination, but there will be no STOP TSONGAS campaign the way there was against Jehlen.