As she introduced Sen. David Zuckerman (P/D-Chittenden) Thursday evening at the Vermont Comedy Club, Sherry Corbin recalled the trepidation many legislators felt in 2000 as they debated whether to allow same-sex couples to form civil unions.

"David was not one of those fearful politicians," the Vermont Freedom to Marry board chair told an audience of 150 packed into the Burlington venue. "From the get-go, David was outspoken in his support of full marriage equality — not just a half-measure."

So against her organization's advice, he and fewer than two dozen others stood up on the floor of the House — where he then represented Burlington's Old North End — and voted to fully legalize gay marriage, not just civil unions. 

"David was going to stand there and vote for marriage equality, whether we told him not to or not," Corbin said. 

Fifteen years later, as Zuckerman formally kicked off his campaign for lieutenant governor, he and his supporters appeared intent on reminding voters that he is no Johnny-come-lately to progressive causes. As the Hinesburg farmer prepares to face off against two twenty-somethings and possibly a thirty-something in the Democratic primary, they argued that he's the one with the experience to get the job done.

"For a guy of 44, David has the chance to be the graybeard of this primary," joked Sen. Phil Baruth (D-Chittenden) as he delivered a surprise endorsement to his colleague and seat-mate. "He knows the House. He knows the Senate. I trust him to preside over the Senate fairly and objectively. I trust him to be an honest broker for senators of all parties. I trust him, is what it boils down to."

Baruth's presence at the event — and his full-throated support for Zuckerman — came as a surprise. For months, the Democratic majority leader had himself been exploring a run for the job. But as he explained afterward, legal ambiguity over the state's public election financing law led him to believe that he would have had to raise gobs of money to compete — something he felt he did not have time to do while helping to run the Senate.

Though he described Zuckerman as indispensable to the Democratic caucus, Baruth was the sole Democratic senator to appear at the event. Otherwise, the dimly lit club was filled mostly with liberal activists and members of the Vermont Progressive Party — in stark contrast to opponent Kesha Ram's campaign launch, which featured many of her House colleagues and figures in the Vermont Democratic Party establishment.

Zuckerman will have to bridge that partisan divide as he seeks both the Democratic and Progressive nominations for lieutenant governor. He's done it before. After winning election to the House seven times as a Prog, he won two terms in the Senate as a Democrat and Progressive.

This time around, he faces Ram — a four-term Democratic state representative from Burlington — political novice Brandon Riker of Marlboro and potentially former journalist Garrett Graff in the Democratic primary. Former senator and auditor Randy Brock is the sole entrant in the Republican primary. Dean Corren, who won the Democratic and Progressive nominations for lieutenant governor in 2014, was in the audience Thursday evening, but he said afterward that he had not yet decided whether he would run for the same office, or for governor, in 2016.

Incumbent Lt. Gov. Phil Scott, a Republican, plans to leave the office to run for governor.

Zuckerman appeared eager to cast his lot with a better known progressive than himself. After taking the stage, he noted that U.S. Sen. Bernie Sanders (I-Vt.) was serving as mayor of Burlington when Zuckerman moved to the city in 1989 to attend the University of Vermont. 

"At that time, he was just beginning to show the state how to take on the political establishment, fighting for the values most of us share but many are too afraid to espouse when they're up for election," Zuckerman said of the now-presidential candidate. "There are a lot of pieces of this campaign that excite me, but I have to say, it's particularly thrilling to be running in the same year Bernie is taking the country by storm."

The candidate wasn't the only one to invoke Sanders' name. In introducing him, ice cream magnates Ben Cohen and Jerry Greenfield, both of whom have been stumping for Sanders around the country, compared the state senator to the U.S. senator.

"Dave has shown that he is relentless in pursuit of his principles and values — a lot like a guy we know who's running for president," Cohen said. 

Zuckerman spent little time outlining specific policy proposals, preferring to paint his platform in broad brushstrokes. If elected, he pledged, he would "make college more affordable," fight climate change and "rebuild our infrastructure," though he left to the imagination how he would accomplish such objectives in an office with few explicit powers.

Of any issue, he spent the most time discussing his desire to "end the failed Reagan-Nixon-and-whoever-else-you-want-to-name war on drugs" by legalizing marijuana. After arguing that "public policy is stronger when it reflects reality," he jokingly asked his audience to "raise your hand if—" before cutting himself off.

In her own introductory speech, climate activist and 350.org board chair Kathryn Blume highlighted the candidate's "fearless and unwavering support of putting a price on carbon pollution." Referring perhaps to Ram, who recently walked back her support for a carbon tax she cosponsored, Blume added, "Not everybody is willing to stand up for it and Dave Zuckerman is."

But after the event, Zuckerman, too, backed away from the legislation, saying he supported "the sentiment behind it," but not the bill as drafted. He said he worried it would overly burden those who drive long distances in rural Vermont and would be impractical if neighboring states failed to pass similar laws. 

Asked if he would vote for the bill if it reached the Senate floor the next day, he said, "I think it's incomplete because of that border issue."