CEDAR RAPIDS, Iowa — Joe Biden said Monday that he sees little hope for a compromise in Washington on guns, adding that President Donald Trump “has no intestinal fortitude” to follow though on his talk of pushing Congress to act in the wake of yet another mass shooting.

The former vice president and 2020 front-runner has made his ability to work with Republicans a touchstone of his presidential campaign, but he told reporters in Iowa that guns will not be the place for that.

“I said I'll work with Mitch McConnell where we can agree. But on this one, he's not going to agree ... so we just have to beat him, flat out beat him,” Biden said a Labor Day picnic in Cedar Rapids. “I think there's no compromise. This is one we have to just push and push and push and push and push. And the fact of the matter is, I think it's going to result in seeing some of them [Republicans] defeated.”

Guns are an issue on the agenda for Congress when it returns to Washington this month after the August recess, but Biden said he’s not holding his breath for action.

Part of the problem, he said, is that Trump has on several occasions voiced some support for new gun safety measures, only to backtrack later.

“I've seen nothing,” he said of a possible solution in Congress this fall. “The president has no intestinal fortitude to deal with this. He knows better. His instinct was to say yeah, we're going to do something on background checks. What's he doing? Come on. This is disgraceful. This is disgraceful what's happening.”

Biden has long positioned himself as a foe to the National Rifle Association and one of the few Democrats who has actually beat them, citing his work to pass the 1994 assault weapons ban that was attached to his controversial crime bill.

More recently, he joined with other 2020 presidential candidates in calling for a gun buyback program for assault-style weapons, which would ban future sales as well as attempt to eliminate some of the guns already in circulation.

Biden, however, believes the program should be voluntary while other candidates have called for it to be mandatory.

Montana Gov. Steve Bullock, another 2020 candidate who attended the picnic on Monday, said when asked about Biden's comments, "I think we should be pushing for progress and pushing for progress now."

"I'll tell you — give you at least 30 million reasons why nothing's happened so far, and that's the 30 million bucks the NRA spent on Donald Trump," Bullock said, adding that Democrats agree on "common-sense" measures such as red flag laws and universal background checks. "The vast majority of NRA members want to see them done," he said.

Sen. Elizabeth Warren, D-Mass., echoed the point while speaking with the news media in New Hampshire, telling NBC News that she would support a voluntary buyback program as part of a multifaceted approach to reducing gun violence, which she would treat as a public health emergency.

"[W}e know what the pieces are," the 2020 candidate said. "So the question — universal background checks, assault weapons off our streets, get rid of bump stocks and the ability to fire weapons in a short period of time. There are a lot of things we could be doing. So why doesn't it happen? And the answer is corruption. It's corruption. Right now we have a Washington that is held hostage by the gun industry and the NRA. That has to stop."

Meanwhile, former Texas Rep. Beto O'Rourke drove Monday morning from his home in El Paso to Odessa, Texas, one of the sites of a mass shooting Saturday that left seven dead and 22 injured.

O'Rourke met with shooting victims at Medical Center Hospital in Odessa and then visited an AFL-CIO Labor Day picnic, where he recounted what he had seen.

"I walked in that door and met a woman in tears," he told reporters. "We hugged each other before I ever knew what had happened to her. Her brother was killed in front of his kids and in front of his wife, and she said, 'I am so angry.' This should not happen. ... And the answers to this are pretty clear. We have too many guns. We have 330 million Americans, 390 million guns in this country."

O'Rourke has become one of the most vocal advocates of gun control in the crowded 2020 field after a gunman targeting immigrants killed 22 people at a Walmart in El Paso last month.

"We have put profits and industry, political action committees ahead of the lives of our fellow human beings, and our fellow human beings — regardless of party affiliation, regardless of whether or not they own they own a gun, regardless of geography — are fed up with it," he said in answering a question about his outspokenness on the issue. "They are just as angry as the woman I just met is. And they want us to do something about it. So, now is the perfect time — in fact, the essential time — for us to talk about it."

Saturday's mass shooting in Odessa and Midland in has also drawn attention to new state laws that took effect Sunday after being signed into law in June by Gov. Greg Abbott, that makes it easier to have guns in schools, government buildings and places of worship.

One law, for instance, prohibits local school districts from putting tough restrictions on how guns are stored in cars in school parking lots.

Biden slammed the new laws as “absolutely irrational” and in service to the “special interests” of the NRA and other pro-gun groups.

“We're talking about loosening access to have guns, be able to take them into places of worship, store them in school," Biden said. "I mean it's just absolutely irrational. It’s totally irrational. It is just a bow to the special interests of the gun manufacturers and the NRA. It's got to stop.”