Presidential candidate Andrew Yang plans to challenge Sen. Elizabeth Warren (D-Mass.) on the issue of Social Security at Thursday's primary debate, as he seeks to make the case that his universal basic income proposal is the most ambitious expansion of the entitlement program in U.S. history.

Yang, a Democratic outsider whose fervent base of online and grassroots support has propelled his unlikely run through the primaries, has made a universal basic income the cornerstone of his presidential bid.

Under Yang's plan, every U.S. adult would be given $1,000 a month. The tech entrepreneur has touted the proposal as a way to address working class jobs that are being lost to automation.

A source inside the Yang campaign told The Hill that he will make the case on Thursday night that Warren's proposal, which would increase Social Security payouts by about $200 a month, is insufficient and that workers should not have to wait for retirement "to receive their dividend as the shareholder of the wealthiest country in history."

Following the Democratic debate, the Yang campaign will begin running a new digital ad called "Social Security" to highlight his plan.

"Social Security is a lifeline, but millions of seniors have to keep working just to get by," Yang says in the ad.

"My proposal? Give every American $1,000 a month. That's in addition to current Social Security benefits, making it the largest increase seniors will receive in history. Big corporations make billions in profits while paying nothing in taxes. It's time to rewrite the rules to make them pay their fair share so all Americans can have the future they deserve."

Warren has slipped in the polls in recent weeks, but she remains a top contender for the Democratic nomination.

Yang raised $10 million in the third quarter and an additional $2 million over 10 days in December while he was on a campaign swing through Iowa. He is one of only seven Democrats to qualify for Thursday's debate in Los Angeles, but has struggled to gain traction in public opinion surveys.

The RealClearPolitics average finds Yang at 2.5 percent support in Iowa and about 4.5 percent in New Hampshire. Still, most surveys find voters don't know enough about Yang to form an opinion.