Rep. Adam Schiff's Republican challenger in California's Senate race, Steve Garvey, owes at least $350,000 – and up to $750,000 – in back taxes, according to his February financial disclosures.

Garvey told Fox News Digital in a statement on Friday: "We have been taking this very seriously and have always filed our taxes on time."

"We have been working diligently with our accountant and the IRS to resolve this debt by the end of the year," he said.  

The financial disclosures, filed by Garvey in the Senate Office of Public Records, show that the former MLB player racked up between $250,001 and $500,000 in federal tax liabilities in 2011, and owes between $100,001 and $250,000 in tax liabilities in the state of California.

The statement also says he owes an 8% interest rate on both liabilities listed. It's unclear whether the taxes are a reflection of business- or self-incurred liabilities. 

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Steve Garvey

Garvey owes at least $350k in taxes.  (Steve Garvey)

Garvey will face Schiff, one of the leading Democrats in the U.S. House, in November to determine who will serve in late Sen. Dianne Feinstein's seat. California puts all candidates, regardless of party, on the same primary ballot, and the two who get the most votes advance to the general election. Among the other big names on the ballot were Reps. Katie Porter and Barbara Lee, both Democrats.

Garvey has campaigned on a platform highlighting crime and homelessness in the state, pledging to get the issues under control. Schiff has taken a more progressive stance.

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Adam Schiff

Garvey's opponent. Rep. Adam Schiff.  (Mario Tama/Getty Images)

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A Republican hasn’t been elected to represent California in the U.S. Senate since Pete Wilson in 1988, when he won re-election over Leo T. McCarthy. Wilson stepped down when he became governor of California in 1991 and appointed John Seymour to serve in his place.

Feinstein defeated Seymour in the state's 1992 election and held the seat until her death in September. Now-Sen. Laphonza Butler was appointed to serve out the remainder of Feinstein’s term.

According to the latest primary results on Friday, Garvey is just slightly behind Schiff at 31.5%, compared to Schiff's 31.6%. Final results will be certified on April 12 after all of the mail-in ballots are counted.

Fox News' Stepheny Price contributed to this report.