What if the Green Party's gubernatorial candidate Jill Stein and Democratic nominee Shannon O'Brien were to make a deal whereby the Greens agreed to vote for O'Brien to get something in return? Some Stein sympathizers raised the question on Saturday, following a visit to Amherst by Robert Reich, the charismatic runner-up in the Democratic gubernatorial primary who is now stumping for O'Brien. Reich, a progressive Democrat whose candidacy was wildly popular in the Valley, is urging his supporters not to vote for Stein, because it could siphon votes from O'Brien and help to elect Republican Mitt Romney. O'Brien and Romney were tied in the most recent WHDH-TV/Suffolk University poll, and 3 percent of those polled said they favored Stein. The other two candidates, Libertarian Carla Howell and independent Barbara Johnson, followed with 1 percent each. Stein supporters say O'Brien isn't strong enough on the issues they care most about, including the environment, affordable housing, tax reform and creating a single-payer health care system. They say Democrats had a chance to neutralize the potential "spoiler" effect Stein's candidacy could have by instituting the electoral reform known as instant runoff voting. Under that system used in other countries, voters specify the order in which they support multiple candidates running for the same office. If no candidate gets more than 50 percent of the vote after a first count, the person with the fewest votes is eliminated and the vote re-tallied. The votes of those supporting the eliminated candidates then go to their second choice on down until one candidate emerges with a majority. If the system was in place, Stein supporters could indicate O'Brien as their second choice and their votes would go to her if Stein was eliminated. In the Green Party's view, Massachusetts Democrats have dragged their feet on that reform and others out of arrogance. "We've been proposing IRV (runoff voting) for a long time and we've been letting the Democrats know exactly what it would come down to, and they have refused to engage in a dialogue about it," Stein said in an interview Sunday. "It's small change between O'Brien and Romney." As for whether Green Party supporters would agree to vote for O'Brien if the Democratic nominee assured them she would campaign for instant runoff voting, Stein said it seems unlikely that O'Brien, as governor, could persuade the Legislature to pass the electoral reform even if she wanted to. But, Stein added, "If the offer came, we would certainly give it consideration. We wouldn't dismiss it out of hand." O'Brien's campaign spokesman Adrian Durbin said O'Brien likely would not dismiss a discussion of a deal either. Referring to instant runoff voting, Durbin said, "I'm sure it is something she would be willing to consider." Said Durbin: "As Shannon has said in the past, she and Jill have many of the same progressive values. We certainly hope that any voter who is committed to electing a governor will support Shannon, because she is the only candidate with those values who can win this election." Amherst lawyer Peter Vickery, one of the chief proponents of instant runoff voting in Amherst, doubts a deal involving that could be brokered between O'Brien and Stein, although he believes that if the two campaigns were able to work out a much more comprehensive package, Green Party members might be persuaded to cast their votes for O'Brien. "I can imagine a situation where a Green candidate and a Democratic candidate could agree that the Democrat would prioritize issues that were dear to the Greens' hearts, and in response, the Green candidate would step out," Vickery said. "But I don't see it happening this time because there is a significant difference between O'Brien and Jill."