(CNN) Throwing down the tax return gauntlet against both Democratic Sen. Bernie Sanders and President Donald Trump, Sen. Kamala Harris of California released 15 years of her tax returns, the most of any 2020 Presidential candidate.

Harris released her taxes from 2004 to 2018, "making her the most transparent candidate in the field when it comes to information about personal finances," said a campaign aide. "This is a stark contrast with President Trump, who refuses to release his tax returns."

The aide added Harris supports congressional legislation requiring a president's tax returns be made public.

Sanders, who has repeatedly promised to release his tax returns and recently revealed his book deals made him a millionaire , is expected to release his returns on Monday, the tax filing deadline for 2018.

According to Harris' tax returns reviewed by CNN and Tim Steffen, director of Advance Planning at Baird, the California Democrat and her attorney husband, Douglas Emhoff, reported an adjusted gross income for 2018 of $1,889,156. Emhoff, an entertainment and intellectual property lawyer and law partner at DLA Piper Law Firm, brings in the overwhelming bulk of the couple's wealth and investments.

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