(CNN) Congressional Republicans have twisted themselves into all sorts of knots in an effort to defend President Donald Trump's conduct with Ukraine. But on Sunday, Oklahoma Sen. James Lankford dipped to a new low.

Appearing on ABC's "This Week," the Republican senator was asked by host George Stephanopoulos whether he believed it was acceptable for a president to ask a foreign country to investigate one of his potential political opponents -- citing not just the much-disputed July 25, 2019 call between Trump and Ukrainian president Volodymyr Zelensky, but also Trump's comments on October 3, 2019 , in which he urged Ukraine and China to investigate Joe and Hunter Biden.

STEPHANOPOULOS: He's asking the Chinese, he's asking the Ukrainians to investigate the Bidens. Do you think that's appropriate?

LANKFORD: Well what the President's trying to express there is his frustration that no one's paying attention to what is potential corruption with the Bidens in the past, that everyone seems to be focused on him, that he's been through two-and-a-half years of investigation in the Mueller report, everyone's been focused on him but no one seems to want to even ask the question about was there potential corruption here --

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