BOSTON — A group of scientists and their supporters are set to march Sunday in Boston’s Copley Square in an event they’ve dubbed “a rally to stand up for science” in the Trump years.

Inside a large nearby convention center, meanwhile, the annual meeting of the American Association for the Advancement of Science (AAAS), the United States’ largest general scientific society, has featured speeches and panel sessions further underscoring the sense that under President Trump, scientists could face wide-ranging political conflicts and challenges, and will have to decide how to meet them.

At the opening plenary, the chair of the board of the AAAS criticized Trump’s executive order on immigration; the next night, a prominent historian suggested to scientists that there’s nothing wrong with taking political stands. Einstein did it, after all, over the atomic bomb.

“We live in a world where many people are trying to silence facts,” said Harvard scholar Naomi Oreskes. She told a vast hall of hundreds of scientists that history does not support the idea that “taking a public position on an urgent issue undermines the credibility of science.”

And yet the challenges for scientists during the Trump administration could not only be bigger, but also potentially more diverse, than those seen during George W. Bush’s administration — a key reference point in the research community for thinking about problems at the intersection between science and politics.

During the Bush years, a number of science controversies arose related to suppression of scientific information or interference with its dissemination, as numerous government scientists and experts charged they’d been blocked from speaking to the media, or that scientific documents had been politically edited.

In those days, the threat of deep cuts to research funding didn’t loom so large as it does now. And today’s science world has also mobilized over Trump’s immigration executive order; more than 100 scientific societies and universities registered their concern in a recent letter to the president.

The anticipation of a multi-pronged battle is shared by the marchers, organized by the Natural History Museum, ClimateTruth, the Union of Concerned Scientists, and numerous other groups.

“It’s so many different fronts — subtle, not so subtle, things that can affect directly or indirectly the health, the environment, the economy, all of these things,” said Astrid Caldas, a climate scientist with the Union of Concerned Scientists who was set to speak at the march. “Depending on if we are talking about an executive order, or the gutting of EPA. So it’s a complex situation, and it’s a unique situation.”

The organizers of the march — a smaller scale version of a major March for Science planned for Earth Day — charge that “from the muzzling of scientists and government agencies, to the immigration ban, the deletion of scientific data, and the de-funding of public science, the erosion of our institutions of science is a dangerous direction for our country.”

Inside the conference Friday, however, more cautious science policy experts warned that Bush-style problems over the suppression and interference with science have not yet clearly emerged under Trump. They stressed that temporary communication freezes during a government transition are not abnormal, and that there are new protections in place for scientists, such as federal scientific integrity directives, that didn’t exist in the Bush years.

“It’s too early to say that there is going to be some across-the-board freeze on the ability of scientists to communicate,” said Joanne Carney, director of the office of government relations at the AAAS, at the Friday science policy panel. “We have [government] scientists attending the conference here. I think it’s a little too early to say that scientists are going to be inhibited and incapable of speaking or publishing their research. But we are monitoring it.”

Granted, that doesn’t mean that federal researchers aren’t already self-censoring out of concern for what they may face.

“Fear is higher,” said Robert Cook-Deegan, a science and health policy expert at Arizona State University, at the Friday session. “If you’re a federal employee, I think there’s going to be a level of self-scrutiny that is higher than it has been in past administrations.”

However, the speakers underscored that scientists could simultaneously face a vast new challenge over securing federal research funding and maintaining it at current levels.

Citing federal budget trends, with an expected tax cut and infrastructure spending program as well as a possible dismantling of the Affordable Care Act, William Bonvillian, director of MIT’s Washington office, said that discretionary federal spending is set to be squeezed. That, in turn, can be expected to hit scientific research budgets, he said, and in turn, the federal and university based research community.

“There is going to be a challenge” to research and development programs, Bonvillian said. “We’re going to need to tell the story, that R&D is actually a key part of the solution, it’s part of growth. But the challenge this time in telling that story is going to be even greater than usual.”

That is a contrast with the Bush years, when the president’s science adviser, John Marburger, extolled the administration’s commitment to scientific research funding. And sure enough, based on data from the AAAS, science funding fared relatively well in the Bush years, especially when it came to defense-related research and development. (Research spending has declined as a percentage of U.S. GDP, but that’s part of a long-term trend that has persisted across many administrations and many years.)

There is particular concern right now about cuts to the Environmental Protection Agency and how those would affect its science. The conservative Heritage Foundation, influential with the Trump administration, has also suggested cutting an entire Energy Department office, the Office of Energy Efficiency and Renewable Energy, which would be a major blow to renewable energy research.

In contrast, medical research would appear to face fewer threats. Former president Barack Obama’s top medical research priorities, such as the cancer “moonshot,” appear far more secure than programs at the EPA, the National Oceanic and Atmospheric Administration, and the U.S. Department of Agriculture, Cook-Deegan said.

“There are a lot of people in those programs that are quite worried,” he said. “I think all we have right now is question marks about those.”

And then there’s the subject of immigration restrictions, and how those affect the scientific community, which has traditionally viewed itself as an international enterprise of knowledge and welcomed contributions from a global talent pool.

Academics and scientists have already played a central role in the immigration debate. In Washington state’s thus far successful lawsuit over Trump’s immigration executive order, the University of Washington attested that it had numerous students and professors who were citizens of the seven countries targeted. That included one professor who had to shelve plans to attend a conference outside the United States for fear of not being able to get back in under the order, and one graduate teaching assistant who was traveling outside of the country when it was signed.

“Science depends on openness, transparency, and the free flows of ideas and people,” said Geraldine Richmond, chair of the board of AAAS and a professor at the University of Oregon, at a plenary session Thursday. “Limitations on the ability of scientists to communicate with their peers and with the public through participation at meetings such as this one will harm the scientific enterprise. We must, and we will, continue to speak out publicly on these issues that are so critical for science to flourish and serve society.”

Richmond said some international researchers may not have been able to attend the meeting, or had made a decision not to come, because of Trump’s executive order.