Missouri's Democratic Sen. Claire McCaskill announced Wednesday she will vote against President Donald Trump's nomination of Judge Brett Kavanaugh to the U.S. Supreme Court, citing his positions on "dark money" issues.

McCaskill said in a statement that the recent sexual assault allegations against him are "troubling and deserve a thorough and fair examination by the Senate Judiciary Committee." But McCaskill added that she made her decision based on his positions on campaign finance issues, saying he'll give "free reign" to anonymous donors and foreign governments to interfere with and influence elections.

"It is his allegiance to the position that unlimited donations and dark anonymous money, from even foreign interests, should be allowed to swamp the voices of individuals that has been the determining factor in my decision to vote no on his nomination," McCaskill wrote. She added that she's also uncomfortable with "his position that corporations are people."

McCaskill's decision had been awaited by those watching her close re-election battle with Republican Missouri Attorney General Josh Hawley, who has called for Kavanaugh's swift confirmation. McCaskill is among 10 Senate Democrats up for re-election in states Trump won, and her vote on Kavanaugh could be pivotal to her chances at winning a third term.

Hawley on Wednesday blasted McCaskill for her decision, saying in a statement that "nobody is surprised."

"Claire McCaskill is now 0 for 6 on Supreme Court nominees since she started running for the Senate 12 long years ago," Hawley said. "She has sided with Chuck Schumer every single time - for liberals and against Missouri. Senator McCaskill has forgotten where she's from and become just another Washington liberal."

According to McCaskill's office, she has voted in support of more than two-thirds of Trump's judicial nominations, although she has voted along party lines for Supreme Court picks since she took office.

During McCaskill's 2006 campaign for Senate, she said she opposed former President George W. Bush's nomination of Justice Samuel Alito but would have voted for Roberts. As a senator, she voted for both of former President Barack Obama's appointees: Justices Elena Kagan and Sonia Sotomayor. McCaskill voted against Neil Gorsuch.

Hawley on Wednesday said he will continue to support Kavanaugh "until there is some proof of these allegations," the Columbia Daily Tribune reported .

The sexual assault allegations were brought by Christine Blasey Ford.

Ford, 51, now a psychology professor in California, said a very intoxicated Kavanaugh cornered her in a bedroom during a party in the early 1980s. She said he pinned her on a bed, tried to undress her and clamped his hand over her mouth when she tried to scream. Ford said she escaped only when a friend of his jumped on the bed and knocked them all over.

Kavanaugh denied the claims.

When asked by a reporter at the campaign event whether she believes Ford, McCaskill said she shouldn't be asked to decide without first hearing Ford testify, the Springfield News-Leader reported .

"I don't think that this is a trial, and I don't think I should be called upon to make that decision without hearing her testify," McCaskill said, adding, "I've tried many of these cases where the victim tells their story and the defendant has a different story, and it's a matter of credibility, and I think anybody who makes up their mind without hearing them testify about the facts and the circumstances are doing both of them a disservice."

It's unclear if Ford will testify. Republicans have set a Senate Judiciary Committee hearing for Monday that is supposed to feature Kavanaugh and Ford. But backed by Democrats, Ford has said she wants the FBI to first investigate the alleged incident.

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