In excerpts of the speech released by his campaign, Sanders said "the path that I call democratic socialism" was represented by Roosevelt's Depression-era New Deal policies to put Americans back to work and offer a broad social safety net.
Roosevelt's policies, which included public works jobs, strong banking and financial regulations and the Social Security retirement program, made huge progress in protecting the needs of working families, Sanders said.
"Today in the second decade of the 21st century we must take up the unfinished business of the New Deal and carry it to completion," said Sanders, whose embrace of democratic socialism has drawn fire from Republican President Donald Trump and even some Democrats.
The speech, to be delivered at George Washington University in Washington, was billed by the Sanders campaign as a look at how a strong grassroots effort based on the progressive values of democratic socialism was the best way to defeat Trump.
"We must take the next step forward and guarantee every man, woman and child in our country basic economic rights," he said, including quality healthcare, education, a decent job, affordable housing, a secure retirement and a clean environment.
"This is what I mean by democratic socialism," he said in the excerpts.
Sanders is one of more than 20 candidates seeking the Democratic presidential nomination for the right to challenge Trump in 2020. He consistently places second in opinion polls on the Democratic race.
Sanders' democratic socialist agenda came under fire at an Iowa Democratic dinner on Sunday when former Colorado Governor John Hickenlooper said socialism was bad politics that could cost Democrats the White House. He described it as "the most effective charge Republicans can level against us."
The speech on Wednesday will be the second time Sanders has tried to ease voter concerns about the label. During his first run for the White House in 2016, he acknowledged the socialist tag made some voters nervous with its Cold War-era images of government-controlled economies and gave a speech that also cited Roosevelt's policies as a model for his agenda.
But in an interview on Sunday, Sanders said he thought Americans were more ready for a democratic socialist in the White House than in 2016."What I mean by democratic socialism is creating a government that works for everybody, not controlled either legislatively or politically by a handful of very wealthy people," he said on CNN's "State of the Union" show.