McCaskill's full return , provided Wednesday to The Associated Press, shows she brought in a roughly $86,000 pension on top of her $174,000 Senate salary.
McCaskill claimed about $89,000 in deductions, including more than $78,000 in charitable giving. She filed separately from her husband, businessman Joseph Shepard.
Hawley and his wife filed a joint return and together brought in an adjusted gross income of about $296,000. Hawley earned about $131,000, and his wife Erin Hawley brought in $166,000. They claimed about $39,000 in itemized deductions, including about $18,000 in state and local income taxes paid, $11,000 in home mortgage interest and $10,300 in charitable giving.
Hawley on Wednesday called on McCaskill to release her husband's returns, which she declined to do.
"Claire has filed separately from her husband since they met and will not be releasing his return," McCaskill spokesman Eric Mee said in a statement. "Her family's finances are fully and properly disclosed on her 61-page personal financial disclosure."
Hawley and Republican challengers in past campaigns have attempted to portray McCaskill, ranked the 24th richest member of Congress by Roll Call as out of touch with the concerns of average Missouri voters. Roll Call estimated her net worth at $26.9 million.
While McCaskill says she's spent her career fighting for Missourians on pocketbook issues by supporting policies such as cutting red tape for businesses and federal job training programs, Hawley has described her as "rich and liberal."
Hawley also renewed criticism Wednesday over federal subsidies awarded to low-income housing projects affiliated with McCaskill's husband, saying that Missouri voters "deserve to see how her family has profited during her time in the Senate." McCaskill's campaign has repeatedly said most of the federal payments go to the projects, not the partners, and has described the claim as a "recycled false attack."
McCaskill and Hawley are fighting for a highly contested seat that could play a role in Republicans' attempt to expand the party's slim 51-49 edge in the U.S. Senate. McCaskill is among 10 Senate Democrats up for re-election this year in states that President Donald Trump won. The president won Missouri by 18 percentage points in 2016.
McCaskill's political opponents have long sought to make an issue of her wealth.
McCaskill's last Republican challenger, former U.S. Rep. Todd Akin, also had called on McCaskill to release her husband's tax returns. She refused, noting he was not the candidate.
Akin also ran an ad criticizing housing subsidies financed through the 2009 stimulus act that went to businesses affiliated with Shepard. In the 2006 Senate race, Republican Sen. Jim Talent ran an ad accusing Shepard and McCaskill of using an insurance company based in the Bahamas as a tax shelter, which they denied.
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