Republican Bruce Poliquin has inched closer to Democrat Emily Cain in the race for Maine’s 2nd Congressional District, according to a poll released Tuesday by a Portland firm.

A survey of 186 voters by Pan Atlantic SMS Group gave Cain, a state senator from Orono, 39 percent support to 38 percent for Poliquin, a former state treasurer from Oakland.

Independent conservative Blaine Richardson of Belfast got 8 percent, with 16 percent undecided.

That sample size isn’t ideal, with an error margin of about 7 percent. But Poliquin has moved up since Pan Atlantic polled the race last month. Then, Cain led Poliquin with 36 percent of support to 32 percent for Poliquin. Richardson got 6 percent.

However, other results have put Poliquin slightly ahead in the race to replace U.S. Rep. Mike Michaud, a Democrat running for governor.

A poll of 291 likely voters released Sunday by the Portland Press Herald/Maine Sunday Telegram put the Republican at 41 percent to Cain’s 40 percent. Richardson had 8 percent, with 9 percent undecided.

Yet another poll from mid-September, from Critical Insights, a Portland firm, had Poliquin at 41 percent to Cain’s 36 percent, with Richardson drawing 6 percent. That sampled 295 voters.

The trend line shows a tight race, which is backed up by the high rate of spending in the race.

Outside interests already have spent more than $2 million to boost the party candidates. The candidates have raised more than $3 million.

By both measures, it’s the most expensive House race in Maine since 2000 and probably ever, according to data going back 14 years from the Center for Responsive Politics, a national group that tracks political spending.

Michael Shepherd — 370-7652

mshepherd@centralmaine.com

Twitter: @mikeshepherdme