This post has been updated.

On April 25, a new company called Left Hand Enterprises LLC was formed in Delaware, listing as its address an incorporation service provider in Wilmington.

A few days later, the firm received two big payments totaling $503,133 from Donald Trump's presidential campaign to print and send a major shipment of direct mail. The campaign cut another $227,504 check to Left Hand Enterprises on May 2, new campaign finance filings show.

The rapid series of payments — $730,637 over five days — made Left Hand the 10th biggest vendor to the Trump campaign for the entire election cycle. But why it was hired, and what work it provided, was a unknown even to some top Trump aides.

The campaign's use of the mysterious pop-up firm has surfaced at a time of financial tumult for the Trump operation, which began June low on funds and has come under scrutiny for making large reimbursements to his companies. On Thursday, in a move to reassure donors, the real estate billionaire announced he was forgiving more than $50 million worth of loans to his campaign and converting them into contributions.

Trump campaign officials did not respond to queries about Left Hand for two days, and did only after The Washington Post published a story online raising questions about the firm.

On Thursday evening, Rick Gates, deputy to campaign chairman Paul Manafort, said in an interview that the campaign's point of contact for Left Hand was Darrin Schmitz, president of Persuasion Partners, a direct mail firm located in Madison, Wis.

Schmitz, a former executive director of the Wisconsin Republican Party, confirmed that he started Left Hand. In an email, he said the campaign's then-field director, Rick Wiley, brought him aboard the Trump campaign.

"The campaign reached out looking for higher quality mail at a cheaper price point than what they were getting, and we delivered on that," Schmitz wrote. "As a founder of LHE, I want to expand our client services and grow a new national footprint. It had nothing to do with any one client including Trump." He did not respond to a question about why the company was registered in Delaware.

Wiley confirmed that he sought out Left Hand, writing in an email: "Mr. Trump self-funded his campaign and I wanted to make sure we were spending his money wisely, and were getting the best pricing on the services needed to secure the nomination.  I'm proud of the work I did for Mr. Trump and this vendor saved us tens of thousands of dollars on this project."

Left Hand got its contract at a time when the campaign had two separate budgets: one for headquarters and travel expenses approved by then-campaign manager Corey Lewandowski, and another for state operations overseen by Manafort, according to people familiar with the internal workings. The invoices for Left Hand went through the budget controlled by Manafort, a person with knowledge of the situation said.

When Left Hand was hired, the Trump campaign was already paying substantial sums to another direct mail firm, WizBang Solutions, a Colorado-based company. Mike Ciletti, who serves as director of WizBang, previously worked with Lewandowski when the latter was a top official at the conservative advocacy group Americans for Prosperity, and briefly ran a pro-Trump super PAC.

In an interview with CNN Thursday, where he was just hired as a political commentator, Lewandowski confirmed that Left Hand was not under his purview and said it was tasked with doing direct mail in Nebraska and Indiana.

"I'm not trying to pass the buck," he said. "But I can tell you that if there is anything that has not been appropriate, Mr. Trump will find it and fix it....I was very diligent in watching where the money was spent, and I can tell you that every vendor knows that we deserve that Mr. Trump would get the best price, the best rate."

There is nothing in the public filings to connect Left Hand to Schmitz or Persuasion Partners. Instead, documents link the company to Harry Dougherty, who works as director of finance at The Lukens Company, a direct mail fundraising firm based in Arlington, Va..

On Federal Election Commission reports, the company lists its address as a single-family home on a seven-acre lot in Purcellville, Va., about 54 miles outside of Washington. According to property records, the home is owned by Harry Dougherty's wife, Florence.

The Lukens Company, where Dougherty has worked since 2002, was founded by Walter Lukens, a veteran direct mail strategist who served as an adviser to Sen. Bob Dole's 1988 presidential campaign and was involved in his later campaigns, according to his online bio. Lukens did not respond to requests for comment.

Schmitz said The Lukens Company is not a partner in Left Hand, and that Dougherty was simply "an accountant who helped with the paperwork."

The first two payments to Left Hand were made on April 28 and April 29 -- just days before the crucial May 3 Indiana primary, where Sen. Ted Cruz made his last unsuccessful stand against Trump. Since direct mail firms usually require payment before sending out a shipment, Left Hand would have had very little time to get leaflets to mailboxes in Indiana before voters went to the polls, according to people who work in the industry.

In Indiana, Republican activists recall receiving a mail piece from the Trump campaign around April 26, pictured below.

But that mailer was sent by WizBang Solutions, according to the bulk mail permit identification under the postage, which reads "WBS."

The Trump campaign's most recent payment to Left Hand came May 2, the day before Cruz dropped out, and eight days before the Nebraska primary. At nearly $230,000, it was one of the campaign's biggest expenditures in May, when Trump spent $6.7 million and brought in just $5.4 million.

Several of the campaign's May expenditures have attracted scrutiny, including more than $1.1 million that went to reimburse Trump properties and Trump and his family members for expenses.

Another transaction last month that has garnered attention is a $35,000 payment to a company called Draper Sterling for web advertising; the company's name appears to be a play on character names from the "Mad Men" television show. The company is registered to a Londonderry, N.H., resident named Jon Adkins, who co-founded a biotech company XenoTherapeutics with Paul Holzer. The Trump campaign paid Adkins and Holzer $3,000 each for field consulting in May.

Alice Crites and Anu Narayanswamy contributed to this report.