When former Secretary of Agriculture and Iowa Gov. Tom Vilsack (D) offered introductory remarks at the start of HuffPost and the Open Markets Institute’s Heartland Forum for Democratic presidential candidates on Saturday, he admonished the candidates not to limit themselves to policy details. After all, Vilsack argued, rural Iowans were used to hearing bold promises that politicians often failed to deliver on.

“We don’t need plans. We need a vision that will drive and prioritize what an administration does,” he said.

Over the course of about two hours, Sen. Elizabeth Warren (D-Mass.), Sen. Amy Klobuchar (D-Minn.), former Rep. John Delaney (D-Md.), former Housing and Urban Development Secretary Julián Castro and Rep. Tim Ryan (D-Ohio) did their best to present that vision.

The five Democrats, all of whom save Ryan are running for president, tackled an array of concerns that have particular resonance in rural America, from opiate addiction and suicide to climate change and trade policy.

But more than any other issue, the Democrats were united in their determination to combat corporate consolidation by beefing up antitrust policy, specifically in sectors like agribusiness that have an outsize impact on American farmers.

“I want to see enforcement of our antitrust laws. I’m calling for the breakup of these agribusinesses,” Warren said in her opening remarks.

Klobuchar likened the present-day power of monopolies across different industries to the robber baron era at the turn of the 20th century, noting that even the online airline booking industry is mostly concentrated in the hands of two big companies.

“We are now entering what is essentially a new Gilded Age and we need to take on the power of these monopolies,” Klobuchar declared.

HuffPost Washington bureau chief Amanda Terkel, left, listens as Sen. Elizabeth Warren (D-Mass.) answers a question during Sa

HuffPost Washington bureau chief Amanda Terkel, left, listens as Sen. Elizabeth Warren (D-Mass.) answers a question during Saturday's Heartland Forum.

Castro argued for the federal government to expand the way it looks at the impact of corporate consolidation, so “we not only concern ourselves with the end-consumer price and choice but also what’s happening along the production chain ― the impact on smaller businesses within that production chain.”

“I’m looking at what’s happening in rural America in regard to the concentration of power in the monopolies ― and you know what we call this in Youngstown? It’s a scam,” Ryan said to affirmations of “yeah” and loud applause from the crowd. “It’s an absolute scam.”

Delaney announced that his Heartland Fair Deal, a suite of policy proposals, includes ideas for “doing some things to actually create an antitrust framework that makes sense for our country.”

Of course, the prominence of antitrust policy in the forum was not a coincidence. The Washington think tank Open Markets Institute, which co-sponsored the event with HuffPost, The Storm Lake Times and the Iowa Farmers Union, is devoted to studying antitrust policy.

Still, the crowd at Buena Vista University responded warmly every time the word “antitrust” came up, suggesting there is a real appetite for politicians who can actually ease the burden on rural Americans caused by growing monopolies.

The forum’s focus marks a major shift in the way Democrats talk about the problem of mergers and other forms of corporate consolidation.

For decades, Democrats generally put up little resistance to the corporate-friendly legal theories and policies championed by their more conservative colleagues. As long as there was no ironclad proof that mergers that ballooned the size of companies were not raising consumer prices, the thinking was, corporate consolidation was not a major concern.

The problem right now in Washington is not only there is no help for farmers, it’s that Washington is on the side of making it worse day by day. Sen. Elizabeth Warren (D-Mass.)

But a group of new lawyers and policy experts, many of whom now hang their hats at the Open Markets Institute, argued that growing corporate consolidation had far-ranging negative effects well beyond the price of a product or service when it comes to market. Watered down antitrust laws and enforcement have created conditions that depress wages for workers and farmers, stifle innovation, distort politics and even endanger American supply chains, they argue.

Warren, who has used her perch in the Senate to tackle the effects of consolidation in the hearing aid industry, has likely put forward some of the most audacious ideas for toughening up antitrust regulations.

Earlier this month, she proposed breaking up Amazon and other major technology platforms. And on Wednesday, she rolled out a plan to apply similar standards to major agribusiness firms, as well as to bar foreign ownership of American farmland.

Indeed, farmers have been particularly hard hit by corporate consolidation ― on both ends of their production process. They must typically buy seeds from a small handful of agribusinesses that have the power to charge them high prices, and then sell their crops to another set of corporate players that have the power to pay lower prices.

As Warren is fond of mentioning, farmers now take home just 15 cents on every dollar a consumer spends on food ― the lowest amount since 1993.

“The problem right now in Washington is not only there is no help for farmers, it’s that Washington is on the side of making it worse day by day,” she said in her opening remarks.

Klobuchar, who represents a farm-heavy state just north of Iowa, was also very much at ease discussing the nitty-gritty of agricultural policy. She has introduced legislation placing fees on corporate mergers that would go toward funding investigations into whether companies violated antitrust laws.

“Do you know the first state that had a comprehensive antitrust law? It was Iowa!” she declared, eliciting loud applause from the audience. “Iowa did it in 1888. That’s right. And now we know we have to do it on the federal level and improve some of the laws we have now.”