La CROSSE, Wis. — In two states that flipped from Democratic to Republican in the 2016 presidential race, the devastating floods are focusing voter's attention on climate change — and both parties' response to it.

"My big concern is the environment," said Amy Bouska, a retired actuary, at a town hall event for Rep. Amy Finkenauer, a freshman Democrat from eastern Iowa. "People know that the Canadians are clearing land to plant corn."

"Whether they're attributing it to climate change is another question, but people know things are changing," added Bouska, who voted for Hillary Clinton in 2016.

As midwestern states grapple with historic flooding that is devastating communities and threatening crop rotations and livestock, some voters are demanding action on what they see as the cause: climate change and more extreme weather patterns.

This year, as Nebraska, Iowa and Wisconsin begin their annual thaw, a flash of warm weather, combined with unusually high snowmelt, is making it difficult for the land to dispose of the winter's water. And that's causing pain in parts of the country that delivered the presidency to Donald Trump.

Cut rows of corn stand in a March mix of slush and mud, with water pooling just about anywhere that's flat. Rivers and streams have crested and may rise yet again.

Farm groups say that it's worse than in the past.

That dynamic allows environmental activists to make their case that climate change is to blame.

At another town hall, across the Mississippi River, in La Crosse, Wisconsin, voters told their congressman, Rep. Ron Kind, a Democrat, that the effect of climate change on the farming community was worse than many in Washington might think.

They also implored Kind to support the Green New Deal pushed by Rep. Alexandria Ocasio-Cortez, D-N.Y.

Yet Kind declined to endorse it.

"The rollout of the Green New Deal didn't go very well," he said. "But the aspirational goal of recognizing the danger of climate change is something that we need to recognize and work toward."

That answer left some of Kind's constituents frustrated, and it may contribute to a primary challenge for the 22-year House veteran in 2020.

Later, along the swollen banks of the Mississippi, with sheets of ice gliding downstream to some of the areas hardest hit by the flooding, Bernie Sanders' supporters protested outside a birthday party for Kind, demanding "Medicare for all" and more robust action to counter climate change.

Beth Hartung, a political activist and Sanders supporter, said that she wasn't happy with Kind not committing to the Green New Deal.

"It's not aspirational," she said. "It's doable. We need a bold leader."

Mark Neumann, a retired pediatrician, said that Kind's positions on climate change and his opposition to a single-payer health care system may lead him to challenge Kind next year in the Democratic primary.

"People are being smacked with climate change at a phenomenal rate," Neumann said. "These are issues that go beyond our binary partisan divide."

Neumann knows that he faces an uphill battle. Wisconsin's 3rd Congressional District voted for Trump in 2016 by 2 percentage points after going for President Barack Obama in 2012.

But Kind's deep ties to the community and centrist positions allowed him to withstand a surge of Trump support, winning in 2016 and cruising to re-election in 2018.

"We need a single payer, publicly funded health-care system," Neumann said in an interview. "Everyone in and nobody out."

Asked if a district that supported Trump would elect a Democrat who supported the Green New Deal and a single-payer system, he would only say "it's possible."

"That's what we'll find out," he said.

CORRECTION: (March 19, 2019, 10:14 p.m. ET): An earlier version of this article misstated the first name of a political activist and Bernie Sanders supporter. She is Beth Hartung, not Amy.