Sen. Claire McCaskill Claire Conner McCaskillCORRECTED: Hawley used a state-owned car for campaign travel as AG: report Poll: 33% of Kentucky voters approve of McConnell McCaskill: Lindsey Graham 'has lost his mind' MORE (D-Mo.) on Thursday took aim at MSNBC’s “Morning Joe,” asserting the show is treating Hillary Clinton unfairly.

“Everybody evolves on positions,” McCaskill said of Clinton during a testy interview with hosts Joe Scarborough and Mika Brzezinski.

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“I’ve been listening to you guys this morning and I think some of it has been unfair and not balanced,” McCaskill said of the show's coverage of Clinton’s position on the Trans-Pacific Partnership (TPP).

“I really don’t think that this is an indication that she is somehow unprincipled or weak,” she added. "I think that’s totally wrong.”

Clinton, the front-runner for the presidential Democratic nomination, broke with President Obama late Wednesday by coming out against his Pacific Rim trade deal, which was finalized this week after years of difficult negotiations.

As secretary of State, Clinton had praised aspects of the emerging agreement, leading some to accuse her of reversing her position.

“What I know about it, as of today I’m not in favor of what I’ve learned about it,” Clinton told host Judy Woodruff on PBS’s “NewsHour.”

“I appreciate the hard work that President Obama and his team put into this process and recognize the strides they have made,” she added. "But the bar here is very high, and based on what I have seen, I don’t believe this agreement has met it.”

McCaskill said White House hopefuls from both political parties have shifted on the issues during the 2016 race.

“You look at [Sen.] Marco Rubio Marco Antonio RubioWhite House pleads with Senate GOP on emergency declaration Sixteen years later, let's finally heed the call of the 9/11 Commission Schumer urges GOP to reject Trump's 'destructive' national emergency MORE [R-Fla.] and you look at [former Gov.] Jeb Bush [R-Fla.] and the changes in their position and how they twist and distort themselves to appeal to the same people who want to elect [GOP presidential front-runner] Donald Trump Donald John TrumpREAD: Cohen testimony alleges Trump knew Stone talked with WikiLeaks about DNC emails Trump urges North Korea to denuclearize ahead of summit Venezuela's Maduro says he fears 'bad' people around Trump MORE president, it really is something to see,” she said, citing the pair’s morphing immigration positions.

“I’m glad that Bernie has evolved on guns,” McCaskill said, citing Sen. Bernie Sanders Bernard (Bernie) SandersSenate Dems seek to turn tables on GOP in climate change fight Bernie Sanders Town Hall finishes third in cable news race, draws 1.4 million viewers Woman to undecided Biden: 'Just say yes' to 2020 bid MORE (I-Vt.), Clinton’s closest competition for the party's 2016 coronation. "He is now four-square with us on what we need to do, but Bernie is someone who voted against the Brady Bill.”

“I just don’t hear enough talk about that,” she added.

McCaskill added on Thursday that she is undecided about the TPP herself.

“She and I may disagree with it, ultimately,” McCaskill said. "In fairness to Hillary Clinton, she voted for some trade deals when she was in Congress, and she voted against others.”