The anti-Obamcare, anti-Romneycare Massachusetts state treasurer I wrote about in my column today on the main site is a former Democrat running for governor as an independent fiscal conservative. The question is: Can he win? If the latest Rasmussen poll is accurate, the answer might depend on who winds up being the Republican nominee.

In a three-way race, Democratic incumbent Deval Patrick wins 35 percent. Republican Charlie Baker receives 32 percent. Tim Cahill comes in third at 19 percent, down from 25 percent in the last poll (which might explain why he is making his big push on health care now). But if the Republicans nominate Christy Mihos, the picture flips. Patrick wins 34 percent, Cahill comes in second with 30 percent, and Mihos draws 19 percent.

One risk is that with the conservative vote split, Patrick can be re-elected despite his enormous unpopularity. This poll shows him with a slight plurality even though he’s an incumbent who can’t get more than 35 percent of the vote. Before Cahill entered the race, Patrick was tied with Baker and trailed Mihos by five points. Cahill is drawing 16 to 20 percent of Democrats, but he is running to the right and his campaign is being run by Republicans.

Typically, in these kinds of races the third-party candidate’s support tapers off at some point. Democrat-turned-Reform Party candidate for governor Tim Penny ran even with the two major party candidates in polls ahead of the 2002 Minnesota gubernatorial election but ultimately finished a respectable but distant third. Third party candidates have gained steam in Massachusetts in recent years, however: Ross Perot finished within two points of George H.W. Bush in 1992; the state gave John Anderson and Ralph Nader some of their highest percentages in 1980 and 2000, respectively; Libertarians had double-digit showings in the 2000 and 2002 Senate races.

UPDATE: I should note that the Republican Mihos ran as an independent for governor in 2006 and got about 6 percent of the vote.