The chairman of New York’s Democratic Party on Monday called for a House ethics investigation into George Santos, a Long Island Republican elected last month, following a report questioning whether he misled voters about key details in his background.

The story by the New York Times cast doubt on Santos’s claims that he worked for Goldman Sachs and Citigroup and the basis of his reported wealth as he loaned his campaign more than $700,000 before notching a surprise win that helped provide the GOP with a slim majority.

“This is about one of the biggest messes I’ve ever seen from anyone who is about to become a member of the Congress,” said Jay Jacobs, the New York Democratic Party chairman, adding later, “I think that had voters seen this information, understood the ramifications and how egregious it really was, I don’t see how he would have won the race.”

In a statement, Santos’s attorney criticized the Times without addressing the substance of the report.

“It is no surprise that Congressman-elect Santos has enemies at the New York Times who are attempting to smear his good name with these defamatory allegations,” Joseph Murray said in a statement posted to Santos’s Twitter.

Santos, a staunch supporter of former president Donald Trump who said he attended a rally on the Ellipse on Jan. 6, 2021, defeated Democrat Robert Zimmerman in November. He claimed in an archived version of his campaign website that he “began working at Citigroup as an associate and quickly advanced” and that he “was then offered an exciting opportunity with Goldman Sachs but what he thought would be the pinnacle of his career was not as fulfilling as he had anticipated.”

Representatives for both Citigroup and Goldman Sachs confirmed to The Washington Post that they had no record that Santos worked for either company. References to Citigroup and Goldman Sachs are not on Santos’s current biography page of the website.

Zimmerman, in an interview with The Post, echoed Jacobs’s calls for a probe into whether Santos made false statements on the personal financial disclosure form that candidates are required to file with the clerk of the House.

“An investigation is merited because of the serious allegations of filing false information on his financial disclosure documents and … questions about his finances [and] where his funds came from,” said Zimmerman, calling on the House Ethics Committee and the U.S. attorney’s office to look into the claims.

Some Democrats expressed disbelief on Monday that questions about Santos’s background didn’t surface more clearly during the campaign. Rep. Mondaire Jones (D-N.Y.), a member of the House Ethics Committee, noted his surprise that the issues hadn’t emerged in prior reporting and opposition research, particularly given that Santos had unsuccessfully run for Congress in 2020.

“As someone who’s had every case I’ve ever worked on vetted by opponents in both cycles, it’s difficult to overstate how many people would’ve had to drop the ball in not even verifying the mere fact of Congressman-elect Santos’ prior employment as he ran to flip a key House seat,” Jones tweeted. Jones’s office did not respond to a request for comment.

Zimmerman said the allegations in the Times story are “not a shock to me.” He said his campaign learned about “many of these issues but were drowned out in the governor’s race where crimes was the focus and the media had other priorities.”

An 87-page opposition research report on Santos released during the race by the Democratic Congressional Campaign Committee did not mention some of the issues raised in the Times story. The group’s opposition research relies on public records to verify employment and education, said a Democratic operative who spoke on the condition of anonymity to describe internal processes. The operative also said Democrats had less time and resources than usual to scrutinize Republican nominees’ records in New York because this year’s primary was delayed to August amid a redistricting fight. Even then, Santos was considered a long shot and Democrats had other priorities.

Nonetheless, there were reports during the campaign that raised questions about Santos’s finances. The North Shore Leader reported in September that Santos filed his financial report on Sept. 6, which it said was 20 months late, “and he is claiming an inexplicable rise in his alleged net worth.”

Financial disclosure reports reviewed by The Post show that Santos declared no assets or earned income in his 2020 report, and that his only compensation in excess of $5,000 from a single source came from a commission bonus.

By comparison, in his 2022 financial disclosure, Santos declared that he had assets worth between $2.6 million and $11.25 million. It also said he had income from a family business, the Devolder Organization, between $1 million to $5 million and a salary of $750,000. The Times reported that the lack of information about the company’s clients was a “seeming violation” of the requirement to disclose compensation of more than $5,000 from one source.

Among the assets Santos declared in his current financial disclosure were an apartment in Brazil worth more than $500,000; a checking account worth more than $100,000; and a savings account worth between $1 million to $5 million.

Separately, Santos declared that he loaned his campaign $705,000.

Tom Rust, a spokesman for the House Ethics Committee, declined to comment. Rep. Susan Wild (D-Pa.), the chairwoman of the committee, also declined to comment through her spokeswoman, citing the panel’s confidentiality rules.

Spokespeople for House Speaker Nancy Pelosi (D-Calif.) and Minority Leader Kevin McCarthy (R-Calif.) did not immediately respond to requests for comment Monday.

Delaney Marsco, senior legal counsel for the nonpartisan Campaign Legal Center, said that “there are a lot of red flags” that may merit an investigation. She cited questions about whether Santos made false statements in his financial disclosure report, a potentially serious offense that could be governed by a number of laws.

With the slim Republican majority in the House, some ethics experts doubted whether Santos would face any serious repercussions in Congress.

“The House is responsible for determining the qualifications of its own members, and if we had a system that was genuinely built around integrity, they would refuse to seat this guy and have a special election,” said Norman Ornstein, an emeritus scholar at the right-leaning American Enterprise Institute who helped create the Office of Compliance and the Office of Congressional Ethics. “Of course the odds of that happening are zero.”

Santos previously has been the subject of scrutiny over his attendance at the Jan. 6 rally where Trump falsely claimed he won the election. Santos later said on a podcast hosted by Lara Trump, Trump’s daughter-in-law, that it “was the most amazing crowd, and the president was at his full awesomeness that day. It was a front-row spectacle for me.”

Newsday reported this year that Santos was filmed saying he wrote a “nice check to a law firm” to help get rioters out of prison and comparing the actions of those imprisoned to “breaking into your own house and being charged for trespassing.”

Alice Crites and Michael Scherer contributed to this report.