Two days after Bernie Sanders won Michigan\u0026#039;s primary in a huge upset, the senator was greeted by tens of thousands of Floridians in rallies across the state on Thursday, demonstrating the enormous grassroots support that is challenging Hillary Clinton in states her campaign once considered guaranteed victories.\u0022We just pulled off a major upset in Michigan the other night, and on Tuesday we have five states coming up, including Florida,\u0022 Sanders said in Gainesville, according to the New York Times. \u0022If you guys come out to vote, we are going to pull off another upset.\u0022\u0022I know people keep telling us that we shouldn’t expect too much, but I feel really, really good,\u0022 a Sanders supporter told the New York Times\u0026nbsp;about the senator\u0026#039;s chances in Florida. \u0022I think he has excellent momentum considering I had no idea who Bernie Sanders was last year.\u0022Tens of thousands attended the rallies in Tampa, Gainesville, and Kissimmee.Two rallies in Florida:1. @BernieSanders.2. @marcorubio. pic.twitter.com/1I4q3Ud0iw— John Nichols (@NicholsUprising) March 11, 2016Watch Sanders\u0026#039; full speech in Gainesville, FL, here:In Florida, the senator \u0022contrasted his consistent record opposing offshore oil drilling with Hillary Clinton’s support for a bill that allowed more drilling in the Gulf of Mexico,\u0022 his campaign stated, noting that \u0022the Florida peninsula is especially susceptible to the effects of climate change because of rising sea levels that scientists say threaten nearly one-third of the state’s Atlantic Ocean and Gulf of Mexico coastal areas.\u0022 Sanders also drew attention to his proposed fracking ban, carbon tax, and belief that the U.S. needs to end oil and gas extraction on public lands.The newspaper quoted Sanders telling his supporters in Kissimmee, \u0022If you come out and your friends and family and neighbors come out, we are going to win here in Florida.\u0022 He was met with loud cheers.The Sanders campaign has \u0022a degree of momentum after winning four of the past six states,\u0022 as the Guardian observes. And indeed, Tuesday\u0026#039;s Michigan win provoked a massive flood of donations totaling $5 million from 175,000 individual supporters within 28 hours, U.S. News and World Report reported.To date, the Sanders campaign has raised a historic $94 million from individual donations alone. The average gift of $27 has, in fact, become something of a rallying cry at campaign stops.Sanders is now widely seen as a contender in Florida, Ohio, Missouri, Illinois, and North Carolina, which all hold primaries on March 15 and were once seen as certain wins for the Clinton campaign. While polls still show Clinton leading in those states—although Missouri has not been the subject of a public poll since August—they also show Sanders narrowing her lead.The most recent Quinnipiac poll, for example, released a day after the Michigan upset, shows Sanders closing in on Clinton\u0026#039;s once-significant lead in Ohio. Sanders trails Clinton by 11 points—the same margin Michigan polls showed before his stunning victory—and he ties with Clinton among Ohio Democrats aged 18-44.Sanders attracted a large crowd of over 7,000 at a February rally in Kansas City, and pundits point to Missouri\u0026#039;s large college population and liberal-leaning cities as areas where the senator may garner a majority of votes. Sanders won the Democratic primary in the neighboring state of Kansas by a whopping 36 points.Missouri also has an open primary, meaning independent and Republican voters will be able to vote for the Democratic nominee—in Michigan, which has the same policy, over 70 percent of independents supported Sanders.As Common Dreams reported, Sanders\u0026#039; message resonates with many Rust Belt voters, such as those in Ohio, Illinois, and Missouri, who have suffered from the devastating loss of blue-collar jobs in the wake of so-called \u0022free trade\u0022 deals such as NAFTA, which Clinton supported.Martha Bayne, editor in chief of Belt Magazine, told\u0026nbsp;the\u0026nbsp;BBCon Thursday that mainstream media pundits outside of the Midwest haven\u0026#039;t understood how much Sanders\u0026#039; populism resonates with Rust Belt states.\u0022Everything in the Rust Belt on the policy level seems to be about economic recovery,\u0022 Bayne said. \u0022It impacts education, it impact health, all these other things...I think that that\u0026#039;s why trade specifically and the loss of jobs overseas has become such a focal point—it speaks to everything else.\u0022Clinton\u0026#039;s lead in the polls in Florida, Illinois, and North Carolina is still wide, but the Michigan win \u0022beat expectations everywhere,\u0022 as the New York Times observed.