WASHINGTON -- President Donald Trump's proposed executive order to protect free speech on college campuses follows a growing chorus of complaints from conservatives that the nation's universities are attempting to silence their voices when they're heckled, disinvited or their presence on campus is otherwise discouraged.

Critics counter that conservatives are turning the shared goal of protecting free speech into a partisan fight.

It's unclear what Trump's order will contain, but the administration has been laying the groundwork for it for months.

The Justice Department has filed statements in various lawsuits siding with students who had alleged that schools had infringed on their right to freedom of speech. Former Attorney General Jeff Sessions opined at a forum last fall that the issue had reached a pivotal point, saying "it is time to stand up to the bullies on campus and in our culture."

Education Secretary Betsy DeVos made a similar assessment, saying "administrators too often attempt to shield students from ideas they subjectively decide are hateful or offensive or injurious, or ones they just don't like."

Trump's proposed executive order, unveiled Saturday during a speech to conservative activists, has drawn criticism from some higher education leaders including President Robert Zimmer of the University of Chicago, a frequent champion of free speech. In a campus email, Zimmer said new regulation would be "a grave error" and would give federal officials dangerous authority to interfere in campus speech issues.

"This opens the door to any number of troubling policies over time that the federal government, whatever the political party involved, might adopt on such matters," he said. "It makes the government, with all its power and authority, a party to defining the very nature of discussion on campus."

In his speech Saturday, Trump highlighted the case of Hayden Williams, who was recruiting on Feb. 19 at the University of California, Berkeley, for the conservative group Talking Points USA when two men approached and one punched Williams during a confrontation captured on student cellphones. Neither Williams nor the man arrested for the attack are affiliated with UC Berkeley.

Trump told the conservatives in the audience that Williams "took a hard punch in the face for all of us."

"If they want our dollars, and we give it to them by the billions, they've got to allow people like Hayden and many other great young people, and old people, to speak," Trump said. "And if they don't, it will be very costly."

The University of California system issued a statement Monday calling Trump's proposal "misguided and unnecessary."

"Free speech is a fundamental value of the University of California and we already have strong policies in place that protect the free expression of ideas, regardless of political persuasion," said Janet Napolitano, the system's president. "We do not need the federal government to mandate free speech on college campuses -- that tradition is alive and thriving."

There were multiple hearings on campus free speech during the past two years when Republicans were in control of both chambers of Congress, though an attempt to legislate on the matter made little headway. A bill from former Sen. Orrin Hatch, R-Utah, that would have banned universities from restricting students' political speeches to certain outdoor areas on campus if that activity is lawful, did not make it through committee.

The hearings followed conservative commentator Ann Coulter cancelling a speech at the University of California, Berkeley, amid fears of violent student protests. Sen. John Cornyn, R-Texas, also cancelled a speech after opposition from students at a historically black university.

Democratic lawmakers have said free speech infringement is just as likely to come from the political right as from the political left. Rep. Bobby Scott, D-Va., encouraged the administration during a congressional hearing last fall to take action on what he called a troubling rise in hate speech on campuses.

"We have seen active investigation of claims of campus free speech violations at public universities brought by conservative activists, but nothing investigating the explosion in incidences of racially motivated hate speech or actions on campus," Scott said.

Terry Hartle, senior vice-president at the American Council on Education, called the proposed order a "solution in search of a problem," adding that free speech is already a core value in American higher education.

"I understand it's sort of a red meat issue for conservative political organizations, but in the real world it's not as big a deal as they would like to believe," he said.

Hartle worries an executive order would empower provocateurs who seek to roil campus audiences, and if campus events threaten to become violent, it could force schools to choose between preserving their federal funding and ensuring campus safety.

Debates over free speech have flared up at colleges across the country in recent years, often sparked by speakers with widely polarizing views. Protesters have shut down events featuring conservative speakers at schools including Berkeley, Middlebury College and several others.

In some cases, schools have cancelled events over fears of violence. Several took that step following a 2017 white supremacist rally that started at the University of Virginia and later became violent. Days later, Texas A&M cancelled a campus event billed as a follow-up to the Virginia march.

Danny Pugh, Texas A&M's vice-president for student affairs, said the school is "in good shape" to handle any executive order, but he added that safety will continue be a priority when weighing free-speech questions. Still, he noted that the vast majority of campus events, even those featuring controversial speakers, go smoothly.

"We sort of get blinded by the provocative piece," he said. "For every one of those, there are thousands plus on our campus that happen without fanfare."

Some observers have raised concerns that an executive order could force religious institutions to host speakers with views that run counter to the school's values. But some prominent religious colleges said they support Trump's proposal, including leaders at Liberty University, a Christian school in Virginia.

"Not only do we encourage speakers with views conflicting universities to come, we pester them to come," said Scott Lamb, vice-president at the school, adding that recent speakers have include former Democratic President Jimmy Carter and Sen. Bernie Sanders of Vermont, an independent.

The school's president, Jerry Falwell Jr., said in an opinion piece for Fox News saying that the "silencing of conservatives on college campuses is serious problem that has spread across our nation."

"Even when administrators don't actively prevent conservatives from speaking on campus, individual extremists sometimes take matters into their own hands by physically assaulting the speakers," he said.

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Binkley reported from Boston.