HELENA — The Democratic candidate for Montana’s sole U.S. House seat, a cowboy poet and musician running for public office for the first time, underreported $57,000 in income when he filed federally required financial disclosure statements two months ago.

Rob Quist has garnered national attention in his bid to become the first Democrat to hold the congressional post in 20 years, but he has come under scrutiny for a history of financial difficulties.

Quist’s campaign filed a new disclosure statement with the U.S. House last week after The Associated Press sought an explanation for discrepancies in his initial disclosure document and on his 2016 income tax returns. Federal ethics law requires congressional candidates to file a one-time accounting of their personal finances.

Montana voters go to the polls May 25 to fill the seat vacated by Ryan Zinke, who resigned to join President Donald Trump’s Cabinet as Interior secretary. Quist and two others who have never held public office are vying for the post — Libertarian Mark Wicks and Republican Greg Gianforte, a wealthy technology entrepreneur who ran unsuccessfully for governor last year.

Quist campaign spokeswoman Tina Olechowski said the updated disclosure was routine, asserting that Quist and his wife did not have a full accounting of their income when he completed his initial report. His original statement was stamped received on March 8 and processed by the House clerk a week later.

“Rob and Bonni amended their personal financial disclosure after they filed their 2016 tax returns so it has the most updated information,” Olechowski said.

She said he had planned to revise his disclosure forms even before the AP began making inquiries.

His updated disclosures show Quist and his wife made about $136,000 in 2016. The original report identified about $79,000 in income, while a copy of Quist’s 2016 tax return released to the AP by his campaign listed a total income of $64,805.

The smaller figure reported to the IRS includes adjustments for business expenses, while his disclosure statement is supposed to list all income sources.

Quist’s financial woes have led to increased scrutiny after revelations that he defaulted on a $10,000 bank loan, did not pay thousands of dollars to a contractor he hired and faced three tax liens from the state over $15,000 in unpaid back taxes.

The liens covered 2007, 2011 and 2012 and were settled last May with the Department of Revenue. Quist has not shared tax returns for those years.

“Once again, Rob Quist was caught not telling the truth, and it’s long past time he release his tax returns for the years in question and finally come clean with Montanans about his trail of tax liens, unpaid debts and underreporting income,” said Gianforte spokesman, Shane Scanlon. “Quist has shown a disturbing pattern of dishonesty, and that record speaks for itself.”

Quist provided AP his tax returns for the past two years, offering a limited glimpse of his finances. In 2015, he and his wife reported $17,504 in income. In 2016, the couple owed $11,484 in federal taxes and $2,030 in state taxes.

During his run for governor, Gianforte released tax returns from 2005 through 2014, showing cumulative income of $220.5 million and total payments of nearly $35 million for state and federal taxes.

He also had a tax lien from 1993 when he lived in New Jersey. The $3,600 lien was settled three months later.

In 2015, Gianforte and his wife, Susan, had an income of $6.5 million, according to a copy of that year’s tax return provided to the AP.

His campaign said his 2016 return was not available because he filed an extension with the IRS. Financial disclosures filed with the U.S. House show his earned income was at least $164,000, with assets ranging between $96 million and $328 million.