WASHINGTON — President Trump plans to propose a reorganization of the federal government as early as Thursday that includes a possible merger of the Education and Labor Departments, coupled with a reshuffling of other domestic agencies to make them easier to cut or revamp, according to administration officials briefed on the proposal.

The plan, which will most likely face significant opposition in Congress from Democrats and some Republicans, includes relocating many social safety net programs into a new megadepartment, which would replace the Department of Health and Human Services and possibly include the word “welfare” in its title.

Mr. Trump and his budget director, Mick Mulvaney, the architect of the plan, have sought to redefine as welfare subsistence benefit programs like the Supplemental Nutrition Assistance Program, or SNAP, and housing aid. It is part of a rebranding effort, championed by conservative think tanks and House Republicans, to link them to unpopular direct-cash assistance programs that have traditionally been called welfare.

“They have been using the word welfare because it is pejorative,” said Elaine Waxman, a senior fellow in the Income and Benefits Policy Center at the Urban Institute, a nonpartisan Washington think tank. “The programs you can call welfare are actually very small in comparison to SNAP, which is an income support necessary to help families, workers and millions of kids.”