Democrat John Hickenlooper and American Constitution Party candidate Tom Tancredo bickered over taxes and education funding in a final appeal for votes before Colorado's gubernatorial election. Hickenlooper, touring the eastern Plains Monday, appealed to philanthropists to rescue underfunded Colorado colleges and universities with a "voluntary tax" -- the same way they helped the homeless in Denver. Tancredo said there is no such thing as a "voluntary tax" and accused Hickenlooper of trying to squeeze the oil and gas industry to pay for higher education. "How voluntary is it when you're the regulating authority?" asked Tancredo, who called it another crazy idea that has emerged in this campaign. Republican Dan Maes spent the day seeking votes in Denver and appealing to supporters via Facebook not to vote for career politicians. He's said cutting taxes and red tape will build the jobs needed to grow the economy and fund higher education. Tancredo has surged in recent weeks thanks to defections from Maes. Hickenlooper has led the race in most polls throughout the campaign but has been stuck below 50 percent. Former Alaska Gov. Sarah Palin endorsed Tancredo Monday, saying: "Hell fight for lower taxes and hell stop growing government and start growing the economy. And we know hell continue working to end illegal immigration." Maes, a Colorado tea party favorite, told KHOW radio he couldn't see where "the courage or integrity is" in Palin's last-minute endorsement. Democratic Gov. Bill Ritter was releasing his final proposed budget Tuesday -- one the winner will have to tackle. Colorado has already covered $4.5 billion in revenue shortfalls over the past three years, and lawmakers believe they will have to cover another $800 million to $1.1 billion next year. Also at stake: Whether the Colorado Republican Party will be considered a minor party if Maes gets less than 10 percent of the vote. A minor party designation would hurt the state party's fundraising and underscore its unraveling in 2010. The little-known Maes jumped into the race in March 2009, followed by former U.S. Rep. Scott McInnis and Republican Senate Minority leader Josh Penry. Their anticipated opponent: Ritter, who surprised all by announcing this year he wouldn't seek a second term. Penry was out after big money Republicans threw their support behind McInnis. But McInnis' campaign imploded in a plagiarism scandal, and the anti-establishment Maes topped him in the August primary. Maes repeatedly rejected GOP efforts to get him to step down, even as he lost prominent tea party and GOP backing. Questions surfaced over his record as a former policeman, his campaign finance violations and his equating a Denver bike-share program to a U.N. conspiracy. Hickenlooper fended off Tancredo's attacks on immigration but was criticized for remarking that some Coloradans were guilty of the same "backwards thinking" that led to the slaying of gay college student Matthew Shepard in Wyoming. Hickenlooper's campaign defended the comment, saying intolerance "is not unique to a single community in Wyoming."