While Cahill has stepped up his criticisms of the governor, Patrick's political team has refrained from striking back, which even Patrick insiders acknowledge. Perhaps that is merely an attempt to avoid further distractions. But some observers say that Patrick wants Cahill to emerge as the only serious challenger, because they believe that, when the time comes, they can beat Cahill like a drum.
Cahill has two obstacles in running as a Democrat against Patrick. First, as the more conservative of the two, he would suffer in the Democratic primary, where votes skew more progressive. (Running as an independent in the general election would allow him to successfully court the votes of independents and Republicans.)
Cahill's second problem is the Democratic Party nominating convention. To get onto the primary ballot, Cahill would need to win at least 15 percent of the delegate votes at next summer's convention.
That might sound like a low threshold, but it could be a major hurdle. Party delegates are not going to be eager to offend the governor or party leaders — mostly Patrick people — by voting for any opponent.
They're even less likely to take that risk for Cahill, who has had a rocky relationship with party insiders.
A minor tempest highlighted this rift in May 2008, when Cahill was denied a last-minute attempt to get elected as an uncommitted delegate to the Democratic National Convention in Denver. Cahill took it as a slap in the face.
In fact, Cahill has never been a favorite of the Democratic Party establishment.
In 2002, most party insiders backed James Segel to succeed Shannon O'Brien as treasurer. Boston City Councilor Stephen Murphy was also running. Cahill, who was Norfolk County treasurer and Quincy city councilor, was seen as an interloper. When Michael Cahill, a fourth candidate unrelated to Tim, was also allowed onto that primary ballot, Tim blamed party insiders for what he saw as a threat likely to siphon his votes due to confusion over the name.
As it happened, the "other Cahill" turned out to be a blessing in disguise: it prompted his campaign to create a commercial in which his daughter Kendra urged voters to choose "Tim for Treasurer." The cute, front-porch, perfect-family ad did more than simply clear up confusion between the two Cahills: it catapulted Tim from unknown to front-runner. Analysts call it one of the most effective ads in the state's political history.
Cahill got just more than a third of the votes, which was enough to win the four-way primary. Party insiders resented him, for (in their view) undeservedly beating their preferred candidates.
"Since then, he's never warmed up to the party," says a Democrat who was closely involved in that 2002 race. "And he's always had a chip on his shoulder."
Cahill's more recent criticisms of Patrick's spending and revenue proposals, and now his open talk of challenging Patrick, has only widened that rift.
"I don't know where Cahill would get his institutional support," says one veteran of state Democratic politics.
But that may be just how he wants it. Some speculate that Cahill is gearing up to run a campaign not just against Patrick, but against Massachusetts's Democratic Party establishment. Cahill will cast Patrick, the onetime outsider, as the cynical manipulator of political machinery, and the Democratic legislature as a bunch of corrupt, self-aggrandizing hacks incapable of reform. He will bill himself, of course, as the outsider coming to clean up Beacon Hill.