Unless undecided voters break for Republican Jason Levesque in a big way, Democratic U.S. Rep. Mike Michaud remains on track to win re-election by a double-digit margin, according to the latest results of The Maine Poll.

The survey results, released Wednesday, showed Michaud leading Levesque by 13 percentage points among likely voters, 43 percent to 30 percent. The big variable is that about one-quarter of the respondents — 26 percent — didn’t know who they would vote for, according to the poll results.

The Maine Poll surveyed the opinions of 300 likely voters in the 2nd Congressional District on Sunday and Monday, and had a margin of error of 5.7 percentage points. The poll was done for MaineToday Media by the Portland research firm Critical Insights.

Michaud, 55, a former mill worker from East Millinocket, is seeking his fifth two-year term in Congress. Levesque, 36, is a businessman from Auburn who owns the Argo Marketing Group.

Compared with the two previous Maine Polls, the third showed Michaud maintaining a comfortable lead. The first poll showed Michaud with a 20-point advantage. The second showed him with a 12-point lead.

Support for Michaud has dropped slightly through the three polls, from 48 percent to 44, to 43. Levesque’s support has gone from 28 percent, to 32, and down to 30.

Even so, Levesque said Wednesday that he was “ecstatic” with the third Maine Poll, because it showed Michaud’s support of likely voters remaining below 50 percent.

“He’s not moving up, and what’s really telling is he’s been on TV (with ads) for a couple weeks now, and he’s going down,” Levesque said. “What that tells me is undecided voters have already fired Mike and they’re looking for a replacement.”

Peter Chandler, a spokesman for the Michaud campaign, said the congressman “is not paying that much attention to the polls.”

“The only poll that really matters is on Election Day,” Chandler said. “We’ve taken this campaign very seriously. From the beginning, we’ve known the midterms would be a tough political environment.”

Chandler said the campaign’s internal polling continues to show greater support for Michaud. He questioned the accuracy of The Maine Poll, with its estimate of one-quarter of voters still undecided.

“Especially with a sample size of only 300,” Chandler said. “The 2nd District has three different media markets, and when you don’t have a large enough sample size, you tend to get a lot of undecideds. We don’t see that large of a number in our internal polling.”

Michaud’s first TV ad shows Maine veterans supporting the congressman, citing his efforts to increase medical access points for veterans throughout the state. Michaud is chairman of the House Veterans Affairs Subcommittee on Health.

“That has been done because he has worked across the aisle with Republicans on his own committee,” Chandler said. “It’s about getting things done for Maine. We’re going to continue getting around to the 11 counties in our district and driving home the message that Mike’s been getting things done in Washington.”

Levesque is taking aim at that very concept. In his first TV ad, released this week, an announcer asks, “Who is Mike Michaud listening to?” and answers that “Nancy Pelosi certainly has his ear,” and Michaud has voted with the controversial House speaker “96 percent of the time.”

The ad says Michaud voted for “Obama’s healthcare takeover,” “national energy tax” and “trillion dollar failed stimulus,” while “Maine lost thousands of jobs and our national debt skyrocketed.”