Eddie Lampert's $5.2 billion offer to buy Sears has entered the political arena, with potential presidential candidate Sen. Elizabeth Warren questioning the billionaire investor's intentions just days before a hearing on the bankrupt retailer's fate.

The Massachusetts Democrat, a longtime critic of unregulated capitalism, attacked the hedge fund manager's track record at Sears, which he ran for more than a decade before the 126-year-old retailer went bust in October.

"It appears that you have enriched yourself while driving the company into bankruptcy," the Massachusetts senator wrote in a letter to Lampert made public on Thursday. Warren also said Lampert, who remains chairman of Sears, has a "history of slashing jobs."

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Lampert and his hedge fund, ESL Investments, have touted their offer for Sears as a way to keep the once mighty retailer alive and save 45,000 jobs. No other potential bidders have surfaced, while the only other option on the table is to liquidate what remains of Sears' assets.

An ESL spokesperson said the fund is reviewing Warren's letter, but defended its bid for Sears, saying it is committed to returning the retailer to profitability and to "save and create jobs."

Lampert and ESL's proposal is expected to be formally approved at a bankruptcy court hearing on Monday.

That hearing prompted a protest Thursday by Sears, Kmart and former Toys R Us workers in a Kmart near New York's Penn Station, where they called on Lampert to set up a financial hardship fund for those affected by store closures.

Sears and Kmart employees are rallying at a Kmart in Manhattan, demanding severance pay and an employee protection fund. The retailer's future may be determined at a bankruptcy hearing early next week. pic.twitter.com/eMKsxuS8VC — Jen Calfas (@JenCalfas) January 31, 2019

The labor group behind the protest, United for Respect's Rise Up Retail, successfully campaigned for two financial firms with stakes in Toys R Us to contribute to a workers' fund.

"Since Eddie Lampert took over, we went from being on top as a retailer to dust," Bruce Miller, a Rise Up Retail leader who worked at Sears Auto in New Jersey for 36 years, said in an emailed statement. "In the span of two weeks, I lost my job, I lost my house and I lost my medical insurance. Now I worry about losing my pension. I'm here today for my coworkers past, present and future."