Intense clashes between anti-war protesters and police on college campuses is spreading alarm among Senate Democrats who worry that anger over President Biden’s handling of the war in Gaza could engulf their party’s presidential nominating convention in late August.

Images of police arresting more than 100 protesters on Columbia University’s campus, including Rep. Ilhan Omar’s (D-Minn.) daughter, have Democratic lawmakers bracing for chaos in Chicago.

It’s just one of several campuses around the country where there have been arrests. 

“I think if the situation doesn’t change dramatically in Gaza, yeah, I think it could be bad,” warned one Democratic senator, who requested anonymity to comment on the growing concern within the party.

“Are you going to the convention? Wear your body armor,” the lawmaker said.

A number of Democratic senators are old enough to remember the violent clashes between police and anti-Vietnam War protesters at the 1968 Democratic Convention in Chicago, where the nomination of Vice President Hubert Humphrey as the party’s presidential candidate was marred by images of police tear-gassing protesters and beating them with clubs.

Sen. Peter Welch (D-Vt.), who attended that convention as a protester against the Vietnam War, said he’s worried protests at this year’s event might overshadow the official proceedings, as they did more than 50 years ago.

“I was there among those who were against the Vietnam War. The demonstrations hurt more than helped, but on the other hand, it’s hard to stop folks who have passionate views about a war. So yes, I do worry,” he said.

Asked if the protests could become violent as they did in 1968, Welch said, “I certainly hope not, that would be terrible.”

“Anybody that gets engaged in violence is going to destroy what they claim is their objective,” he said.

Welch was one of three members of the Senate Democratic caucus to vote against a $95 billion emergency foreign aid package because of military aid to Israel, which progressive critics say will fund the military offensive in Gaza.

Protest organizers expect as many as 30,000 people to show up in Chicago to demonstrate against Israel’s military action in Gaza, almost triple the number of protesters who gathered in Grant Park in August 1968.

Some Democratic officials, however, are questioning if that many people will show up in Chicago, considering other protests have drawn smaller numbers.

The national atmosphere was much more tense at the convention in 1968, which was held a few months after the assassinations of Martin Luther King Jr. and Bobby Kennedy.

American troop deployment peaked in Vietnam that year at 549,000.

Illinois Gov. JB Pritzker said Chicago will be prepared for the protests, but that’s not much comfort to Democrats who remember Chicago Mayor Richard J. Daley vowing to keep the peace by deploying 12,000 police, 5,000 National Guardsmen and 7,500 regular army troops.

The clashes in 1968 left hundreds of demonstrators and dozens of police officers injured.

“Of course there will be protests,” said Senate Democratic Whip Dick Durbin (Ill.), who acknowledged his concern ahead of this year’s convention.

“They’ve been pretty significant up to this point,” he said of the protests at college campuses and cities around the country. “I hope we can manage it. We want to protect our Constitution and also protect all the conventioneers and people in the city.”

Asked if he’s worried about a flashback to 1968, Durbin replied, “Of course.”

“We’re thinking ahead how to handle the security,” he said. “There’s bigger investment by the federal government in these conventions than before.”

The Department of Homeland Security has designated the convention a national special security event, which it also does for Super Bowls, inaugurations and other large-scale events.

Secret Service personnel travel to convention host cities more than a year in advance to plan security. Federal, state and local officials are working together to keep members of Congress and other Democratic delegates safe.

Matt Hill, a spokesperson for the Democratic Convention, said “the freedom to make your voice heard is fundamental to American democracy and has been a fixture of political conventions for decades.”

“The safety of our delegates, guests and visitors is our top priority and we support the ongoing coordination between federal, state and local officials and partners to keep the city secure while respecting rights to peacefully protest,” Hill said.

Anti-war protesters have stepped up their efforts to pressure Democratic lawmakers at political dinners and town hall events and even at their homes.

About 200 protesters were arrested for blocking traffic during a protest near Senate Majority Leader Chuck Schumer’s (D-N.Y.) home in the Prospect Heights neighborhood of Brooklyn.

Hours before the Senate voted to send $15 billion in new military aid to Israeli Prime Minister Benjamin Netanyahu, protesters gathered in Grand Army Plaza around a banner resembling a Seder plate on the second night of Passover inscribed with the slogan: “Jews say stop arming Israel.”

Asked about the protests so close to his apartment, Schumer reiterated his commitment to getting humanitarian aid to civilians in Gaza and minimizing civilian casualties.

Some Senate Republicans, including Sen. Josh Hawley (Mo.), have called on Biden to send soldiers to college campuses to keep Jewish students safe.

About 50 pro-Palestinian protesters disrupted the annual Wayne Morse Gala, Oregon Democrats’ biggest fundraising event of the year, at the Hilton Hotel in downtown Portland earlier this month.

Some of them banged on the hotel’s locked doors and windows, and a few slipped past hotel security to get into the event where they were confronted and escorted out of the building by Portland police.

Sen. Jeff Merkley (D-Ore.) said the protests in Portland and at universities such as Columbia and Yale in recent weeks are a taste of what to expect at the Chicago convention.

“I expect that there will be robust protesting,” he said.

Ross K. Baker, a professor of political science at Rutgers University — another school where there have been protests — said Democrats have good reason to be worried about the convention.

“I’m deeply concerned about the outbreak of violence at the convention. We have not a seen a movement that is capable of disruption like the campaigns on campus currently that are protesting connections to Israel,” he said. “There’s been a really extensive mobilization across the country.”

He warned the divisions among Democrats over the war could hurt Biden’s reelection bid, just like the anti-war movement divided the party in the 1968 presidential campaign, when Humphrey lost to President Nixon in the general election.

Baker said it could “have an impact very similar to the impact it had in 1968, which is to reduce support for the Democratic candidate, in this case President Biden.”

Baker predicted huge crowds of protesters in Chicago, which could “pose a very significant threat to the conduct of the convention itself.”

“For a nominee’s party to have to basically confront people who are ordinarily supporters of the party is both an embarrassment and a serious political problem,” he said.

Chicago Police Department Superintendent Larry Snelling said the police will be prepared to keep the city orderly, noting that command staff who worked on the 2012 NATO Summit, which was hosted in the city and also drew protests, are leading convention planning.

“Our officers are receiving training in anticipation of large demonstrations. This training is rooted in constitutional policing with public safety as our priority,” he said.

The loud and disruptive demonstrations around the country have put Senate Democrats in a tough position because they recognize that many younger voters, whose turnout will be critical to the party keeping control of the White House and Senate, are disillusioned over Biden’s handling of the war.

A New York Times/Siena College poll of 1,059 registered voters nationwide taken April 7-11 found that 45 percent of voters under 30 sympathize more with Palestinians than Israelis in the conflict. Only 15 percent said they sided more with Israel.

A Times/Siena poll conducted in December found that 72 percent of registered voters under 30 somewhat or strongly disapproved of Biden’s handling of the Israel-Hamas war.

Months of pressure from the administration on the Netanyahu regime has had a limited effect on the Israeli military’s tactics or the ability of humanitarian groups to get food and other critical supplies into Gaza.

The World Health Organization reported earlier that only 10 of Gaza’s largest hospitals are somewhat functional because of military strikes on hospitals and ambulances and the trickle of medical supplies that have been able to get into the enclave.

The package Biden signed into law last week included $9.15 billion for humanitarian assistance to Gaza, Ukraine, Sudan and other vulnerable populations around the world.

“I know the president is working very hard to ensure there is a humanitarian response from the Netanyahu government that reflects the concern that the Biden administration and people all around our country are increasingly expressing,” Sen. Ed Markey (D-Mass.) said.

“The goal is to ensure the Netanyahu government is abiding by American international law,” he said.

Asked about the protests at college campuses and town hall events, Markey said, “I hear their voices on an ongoing basis.”