Shumlin was easily favored to win a third, two-year term as governor in the heavily Democratic state. His Republican opponent, Scott Milne, was underfunded and had not run successfully for lower office. His campaign manager resigned just a few weeks before Election Day.
Nevertheless, Shumlin took just 46 percent of the vote, to Milne's 45 percent. "They had an inexperienced candidate who didn't really have a clear message and yet he almost beat Shumlin," said Bert Johnson, a political scientist at Middlebury College.
With no majority winner, under Vermont law the winner will officially be decided by the legislature in January. There's little doubt that Shumlin will get another term, given that both legislative chambers are held by Democrats. The legislature has not picked the second-place finisher for governor since 1853.
That leaves the question of how Shumlin will govern, having been so badly rebuked. "Since the election, we've seen a different governor than we've had for the last four years," said Donald Turner, the Republican leader in the state House. "He has heard what voters intended, that they are not happy with him."
There are various reasons voters were unhappy, including many Democrats. The state's online health exchange has widely been considered a failure. Property taxes are on the rise. Residents of different parts of the state have criticized Shumlin's positions on wind turbines and a natural gas pipeline. A private land deal also played badly for the governor.
"Liberals in the state admire Peter but don't trust him," said University of Vermont political scientist Garrison Nelson. "His battles for a single-payer health care system and GMO food labeling have been well-received, but liberals expect more."
The only public poll conducted during the campaign showed Shumlin comfortably ahead. Many Democrats, dissatisfied with the governor, but not expecting him to be in any trouble, simply didn't vote. Turnout was well down from 2010, with just 193,000 votes cast in the governor's race last month, compared with more than 240,000 four years ago.
And Shumlin is not personally popular. In his four races for statewide office, including one run for lieutenant governor, he only cracked the 50 percent mark once -- in 2012, when he still managed to trail President Obama in the state by 12 percentage points.
Since the election, Shumlin has been making conciliatory statements and reaching out to a wider variety of political players, including Republican legislators.
"The first question he has to answer is what part of Vermont is he now going to listen to," said Joe Benning, the GOP leader in the state Senate. "Is he going to listen to the center, which is very frustrated about property taxes and the economy, or will he go back to the left-wing, asking for more and more programs?"
Shumlin still would like to convert the state to a single-payer health care system. But an ally in that cause, state House Health Care Committee Chair Mike Fisher, lost his race for re-election. And the problems with the health exchange -- a buggy website that was shut for weeks this fall to address technical and security problems -- have not encouraged residents about the state's health management capacity.
"Many people will see the millions spent by the state without successfully fixing Vermont Health Connect as one more proof that government should stay out of health care," Aki Soga, the editorial page editor of the Burlington Free Press, wrote recently. "Even a fully operational exchange will have the state playing catch-up in the public image race."
Getting to a single-payer system "was a heavy lift to begin with," conceded Deb Richter, the head of Vermont Health Care for All, which advocates for such a system. But she said it remains a priority for Shumlin and predicts he'll unveil a financing proposal early in the new year.
Nelson, the University of Vermont political scientist, suggests that Shumlin might as well go for it. Nelson said he admires the governor, but that Shumlin's political future is "bleak.
"Regarding his agenda, I would suggest that he treat this term as his last one and push hard for single payer with guns ablaze," Nelson said.