Democratic presidential candidate Bernie Sanders rallied with thousands of voters in the Kentucky city of Bowling Green on Saturday after spending Friday calling for a ban on fracking in North Dakota.

The Vermont senator stood in one of the largest oil producing states in the US and promised his plan to increase renewable energy would help them transition off fossil fuels.

He also gave a reality check to deniers of the global environment crisis: “The debate is over. Climate change is real.”

The Bismarck Tribune drew comparisons between Sanders’ speech and presumptive Republican nominee Donald Trump’s decision to seek energy policy advice from a climate skeptic, North Dakota's only Congressman, Kevin Cramer, on the same day.

In his speech, Sanders expressed his wish for higher voter turnouts and to maintain a “vibrant democracy.”

He was referring to the current political process as an oligarchy with “a handful of families who control the political life of the nation, who control the economy, who control the media.”

People started lining up for Bernie Sanders rally in Fargo at about 5:30AM for to see candidate Sanders' 2PM rally! https://t.co/4bAFOXKUHt — Michelle (@NewyorkWeissman) May 13, 2016

Sanders leveled a scathing attack on the Walton family of Walmart, revealing the corrupt system that allows America’s largest private employer to pay its workers wages so low, they require food stamps and benefits to survive.

“And who pays for those food stamps and Medicaid? You do!” he reminded the crowd.

June 7 will be crucial for Sanders’ campaign, as both Dakotas, Montana, New Jersey, New Mexico, and the big one, California, vote in primaries.

Hillary Clinton has 1,716 pledged delegates versus 1,433 for Sanders.

Clinton bias accusations chase top Democrat Wasserman Schultz https://t.co/I5xZZeHFMLpic.twitter.com/dfzRGyUbNf — RT America (@RT_America) January 30, 2016

When unpledged superdelegates are added to the equation, it increases Clinton's lead, but they are able to change anytime between now and the Democratic National Convention in July, as was the case in 2008 when many switched from the New York Senator to Obama.

The convention setup has been accused of being unfairly stacked in Clinton’s favor.

Her supporters are disproportionately represented on both the rules and platform committees, despite opposition from the Sanders camp.

DNC packed Democratic convention committees with Clinton supporters – Sandershttps://t.co/ULJl9GTYyxpic.twitter.com/AuTvjTVqMl — RT America (@RT_America) May 6, 2016

A Las Vegas judge on Friday threw out a lawsuit brought by Sanders supporters against the state’s Democratic Party, McClatchy reports.