As Maine voters prepare to cast their ballots Tuesday, a poll released Sunday suggests the race for the Blaine House has tightened and the proposed Taxpayer Bill of Rights is headed for defeat.

The SurveyUSA poll, conducted for WLBZ 2, WCSH 6 and the Bangor Daily News, found that Gov. John Baldacci’s re-election was “likely but not certain” in light of a strong, late-October push by independent candidate Barbara Merrill of Appleton.

The poll, conducted between Thursday and Saturday, shows the Democrat Baldacci at 36 percent, Republican Chandler Woodcock at 30 percent, Merrill at 21 percent, and Maine Green Independent Pat LaMarche at 11 percent.

One percent of those surveyed said they would vote for independent Phillip Morris NaPier, and 1 percent remained undecided. The poll surveyed 638 likely voters. It has a 4 percent margin of error.

While both Baldacci and Woodcock saw their support slip in the past two weeks, according to the poll, Merrill was the only candidate to gain significant ground during that period. Since Oct. 25, Merrill jumped from 12 percent to 21 percent in the SurveyUSA poll.

“This is exactly what I’ve been seeing on the road,” Merrill said when reached on the campaign trail in Bath on Sunday afternoon. “Obviously, this is an incredibly fluid election.”

Among likely independent voters, Merrill, a state representative from Appleton, is up 21 points and Baldacci is down 18 points since September. The two now are tied among this group of swing voters, 31 percent of whom say they will support each candidate.

Baldacci spokesman Jesse Connolly on Sunday said the governor, who has maintained a lead over his challengers throughout much of the campaign, was taking nothing for granted. Last week, a Rasmussen Reports poll found Baldacci at 45 percent to Woodcock’s 31 percent. That poll did not include Merrill or LaMarche.

“We are feeling confident about what we’re doing heading into Election Day,” Connolly said Sunday afternoon from Lewiston while the governor prepared to host one of his trademark spaghetti dinners 100 miles away in Bangor.

The SurveyUSA results didn’t come as a surprise, Connolly said, considering Baldacci’s three chief rivals have used much of their combined $2.9 million in public financing to target the governor.

“It’s important when you recap this election you look at the millions in taxpayer dollars that have been used to attack Governor John Baldacci,” he said.

Baldacci is running a privately financed campaign, while LaMarche, Merrill and Woodcock are publicly financed candidates under the Maine Clean Elections Act.

LaMarche, who will campaign in Bangor today, said she was “absolutely delighted” by the poll’s results.

“It shows there is flexibility and flux in this race,” said LaMarche, although adding she put more faith in a text-message poll her campaign conducted last week showing her in the lead.

Woodcock, a conservative state senator from Farmington, spent Sunday afternoon campaigning in southern Maine alongside backers of the Taxpayer Bill of Rights, a referendum initiative to limit state and local government spending.

Woodcock spokesman Chris Jackson said he thought the poll showed general dissatisfaction with the existing administration.

“It’s extremely competitive, and it’s all about turnout,” Jackson said. “If we turn out our base, we’ll be OK.”

Woodcock’s Sunday stint with the Taxpayer Bill of Rights campaign comes as the spending limits plan appears to be foundering.

According to SurveyUSA, 50 percent of those polled said they were certain to vote against the initiative, which will appear as Question 1 on the Nov. 7 ballot. Thirty-three percent said they were certain to support TABOR and 17 percent were undecided.

The Taxpayer Bill of Rights seeks to limit increases in state and local government spending by the rate of inflation plus population. It also would require voter approval of all tax and fee increases.

Dennis Bailey of the anti-TABOR group, Citizens United, welcomed the poll results in the campaign’s waning days.

“It’s a reflection that the people have zeroed in on this and done their homework,” said Bailey, whose group contends the spending limits will harm local schools and public safety departments while taking budgetary decisions out of the hands of local elected officials. “I think it will be closer, but I do sense things have been trending in our direction.”

TABOR campaign spokesman Roy Lenardson said Sunday he believes the race is closer than the poll suggested. He said voters shouldn’t be fooled by lawmakers’ promises to cut spending without TABOR’s limits in place.

“This is it. This is your last chance,” Lenardson said in a telephone interview from the TABOR campaign’s bus tour stop in Lewiston on Sunday. “If you think for one minute they’re going to change the way they do business with another set of promises, you’re making a big mistake.”