Two years ago, Gov. Peter Shumlin was riding high on a wave of popularity.

The governor's approval rating was 65.1 percent in the spring of 2012, thanks in no small part to the successes of his first term in office. Vermonters overwhelmingly supported his handling of Tropical Storm Irene, and there was broad support for Act 48, the governor's single-payer health care plan. The WCAX/Castleton poll from 2012 showed that 22.6 percent of voters disapproved of Shumlin after his first two years in office.

In a VTDigger/Castleton Polling Institute poll conducted from March 31 to April 6 this year, nearly half of those polled (49 percent) approve of the job that Shumlin is doing. Forty percent of respondents said they disapproved of the governor's job performance.

Eric Davis, professor emeritus of political science at Middlebury College, says Shumlin's popularity has waned since 2012 somewhat due to a variety of factors, including incumbency.

"The passage of time affects every governor," Davis says.

Typically, an incumbent loses 2 percentage points to 3 percentage points over an election cycle, he says.

"I'm not surprised that his [Shumlin's] approval rating is lower than two years ago," Davis said, "but to lose 15 points in two years is a pretty good drop. The question is, why is Shumlin less popular today?"

Davis said there are several plausible explanations. The decline in Shumlin's approval rating could be due in part to stories about the governor's land deal with his neighbor, Jeremy Dodge, last year. Or voters could be disappointed that he missed the deadline for revealing financing plans for single payer health care and has not been transparent about how the program will be paid for.

Respondents to the VTDigger/Castleton poll gave the Vermont Legislature an approval rating of 44 percent. Thirty-three percent disapprove of the Legislature's job performance and 23 percent had no opinion.

The Vermont Legislature has a much higher approval rating than Congress, which came in at 13 percent in January 2014, according to a Gallup poll.

Davis says the Vermont Legislature, which is dominated by Democrats in the House and the Senate, doesn't suffer from same perceptions that Congress does, which has been mired in partisan conflict.

The VTDigger/Castleton Polling Institute poll is based on data from 682 interviews drawn from a random sample of registered voters in Vermont. Interviews were conducted by phone by from March 31 to April 7, 2014. For a sample of this size, the margin of error at the 95 percent confidence level is +/-4 percent, although the margin of error is larger for questions involving subsamples of respondents.