The president is expected to make the announcement on Tuesday that he will end protections for young immigrants who were brought into the country illegally as children, but with a six-month delay, people familiar with the plans said.
The delay in the formal dismantling of DACA would be intended to give Congress time to decide whether it wants to address the status of the so-called Dreamers legislation, according to two people familiar with the president's thinking.
But it was not immediately clear how the six-month delay would work in practice and what would happen to people who currently have work permits under the program, or whose permits expire during the six-month stretch.
MORE: What you need to know about DACA
It also was unclear exactly what would happen if Congress failed to pass a measure by the considered deadline, they said. The two spoke on condition of anonymity because they were not authorized to discuss the matter ahead of the Tuesday announcement.
The organization UndocuMedia held the public rally between 9 a.m. and 1 p.m. Monday in support of keeping DACA. The event was part of a larger Labor Day rally in downtown.
"While losing DACA will be a tragedy, immigrant community and allies have proven time and time again that we are able to heal from attacks like this and come back stronger and united," the group stated in a Facebook post about the rally.
Approximately 200 people held a protest last Friday outside the federal building in support of DACA.
DACA, which was set up by former President Barack Obama by executive order, has given nearly 800,000 young immigrants a reprieve from deportation and the ability to work legally in the form of two-year, renewable work permits. Trump can end the program by executive order as well.
"The 800,000 people now are part of the society. They're part of the economy. They're part of everything. They're contributing. They're already making contributions that is already being seen," said David Huerta with the Service Employees International Union. Huerta took part in Monday's downtown rally.
California is home to about 220,000 DACA recipients, which is more than any other state.
Meantime, word of Trump's expected announcement received reaction from both Republicans and Democrats.
"There are 800,000 DACA kids, kids who were brought across the border, the median age is I think 6 years old for those 800,000 when they came across the border. They should not be punished for the sins of their parents," said Republican Sen. Jeff Flake of Arizona.
California Sen. Dianne Feinstein took to Twitter to voice her support for DACA recipients, saying, "We stand with them. We have their backs."
California Sen. Kamala Harris also took to social media in her defense of DACA, saying, "Ending DACA would be nothing short of heartless" and "there is nothing crueler than deporting" DACA recipients.
There is nothing crueler than deporting kids who grew up in America back to a country they don’t even know. #DefendDACA— Kamala Harris (@KamalaHarris) September 2, 2017
During his campaign, Trump slammed DACA as illegal "amnesty" and vowed to eliminate the program the day he took office. But since his election, Trump has wavered on the issue, at one point telling The Associated Press that those covered could "rest easy."
The Associated Press contributed to this report.