Supporters of Donald Trump and opponents plan to rally in downtown Baltimore today, setting the stage for possible clashes as the Republican presidential nominee addresses the annual conference of the National Guard Association of the United States at the Convention Center.

Trump is scheduled to speak at 1 p.m. today, his first campaign appearance in Baltimore as the nominee. He is to speak to National Guard officers from around the country as national security has emerged as a central issue of the presidential race.

“This is a historic visit,” said Gary Collins, volunteer coordinator with Maryland For Trump. “We're expecting to see a large turnout.”

Maryland For Trump is planning a rally for 11 a.m. outside the Transamerica Building at 100 Pratt St. Organizers urged participants to arrive early and said they would distribute Trump signs.

“You cannot obtain tickets to the speech,” the group wrote on Facebook. “However we have been instructed to line the streets to show our support!”

Meanwhile, the Peoples Power Assembly has organized a protest against Trump. Activists plan to gather outside the convention center at 11:30 a.m.

Some protesters said they would march to the Transamerica Building and confront Trump supporters.

The goal, they said on Facebook, is to “shut down as much of downtown as possible while making some chaos outside the convention center and maybe gaining access to disrupt him speaking.”

Peoples Power Assembly organizer Sharon Black said a space would be designated outside the convention center for those who wish to protest Trump without confrontation.

“There's nothing wrong with a diversity of tactics,” she said. “Some people can engage and others may not be able to do that.”

A Baltimore police spokesman said the U.S. Secret Service was handling security for Trump's visit. Police did not respond Sunday evening to additional questions about security at the protests or possible road closures.

Trump has faced criticism from Democratic nominee Hillary Clinton and others for saying last week that Russian President Vladimir Putin has been a stronger leader than President Barack Obama and that America's military leadership has been “reduced to rubble.”

Maryland, where Democrats outnumber Republicans by more than 2 to 1, has voted for the Democratic nominee in each of the last six elections. A poll released last week by Annapolis-based OpinionWorks found Clinton leading Trump in the state by 29 points.

Collins predicted a “historic turnout” for Trump in Maryland. He cited the Republican's “no-nonsense approach to pressing issues and economic disparity that is facing the vast majority of Americans.”

Black, of Peoples Power Assembly, said Trump's message opposes immigrants, poor families and the lesbian, gay, bisexual and transgender community.

“Trump does not represent the people of Baltimore,” she said.

Baltimore Sun reporter John Fritze contributed to this article.

tprudente@baltsun.com