Paul Heintz

During a U.S. Senate candidate forum Monday night in Winooski, incumbent Sen. Bernie Sanders (I-Vt.) would not commit to serving a full six-year term if reelected.“Right now, my focus is on the year 2018, but if you’re asking me to make an absolute pledge as to whether I’ll be running for president or not, I’m not going to make that pledge,” Vermont's junior senator said. “The simple truth is I have not made that decision. But I’m not going to sit here and tell you that I may not run. I may. But on the other hand, I may not.”Asked again whether he would commit to serving out a third term, Sanders said, “If I’m elected president of the United States? Mmm. Probably impossible to be a senator and a president at the same time. So the answer to that is probably no. But I haven’t made that decision as to whether I’ll run.”He added, “If I run [for president] and win, the likelihood is I will not be Vermont’s senator.”During Sanders’ first term in the Senate, he was present for 98 percent of roll call votes. His record faded after his reelection in 2012, largely because he ran for president in 2016. That year, when Sanders lost the Democratic primary to Hillary Clinton, he missed 115 of 163 roll call votes in the Senate.On Monday, during the debate hosted by Channel 17 and moderated bypolitical editor Paul Heintz, Sanders would not pledge to have an attendance rate above 95 percent in his next term.“I think maybe you didn’t hear me the first time," Sanders said. "I ran for president of the United States. And when you run for president of the United States, you actually go around the country. You have to campaign in order to do that."The senator said he returned to Washington, D.C., for close, important votes during the 2016 campaign, but he denied the fact that he did, indeed, miss more votes than any other senator who ran for president in 2016.Sen. Kirsten Gillibrand (D-N.Y.) is also considered a potential 2020 candidate for president, but she promised voters last week that she would serve out a full six-year term if reelected.Each of the seven other Vermont candidates participating in Monday's debate — Republican Lawrence Zupan and independents Folasade Adeluola, Russell Beste, Bruce Busa, Edward Gilbert Jr., Brad Peacock and John Svitavsky — pledged to serve all six years of the term and miss no more than 5 percent of votes.Svitavsky, unimpressed by Sanders' answer, went a step further with his pledge: "And neither will I be condescending, arrogant or insolent about it.”The event was Sanders' second of the day. He also debated Zupan earlier on Monday.Watch the full forum below: