Democratic presidential candidate Joe Biden said he felt "embarrassed by" Republican Sen. Lindsey Graham's choice to request documents related to his son's time as a board member of a Ukrainian energy firm.

Graham asked Secretary of State Mike Pompeo for access to phone call transcripts between Joe Biden and then-Ukrainian President Petro Poroshenko in February 2016. As House Democrats pursue impeachment of President Trump for urging current Urkainian President Volodymyr Zelensky to investigate Biden and his son Hunter during a July phone call, the president and Republicans have insisted that the Bidens' relationship with Ukraine merits investigation.

Trump and his allies have repeatedly asserted that Biden used his vice presidency to push Ukraine to fire then-Prosecutor General Viktor Shokin to prevent him from investigating Burisma Holdings's owner, Ukrainian oligarch Mykola Zlochevsky, in an effort to protect his son. Shokin was removed from his position in March 2016 at Poroshenko's behest.

"I want to know if there’s any transcript or readouts of the phone calls between the vice president and the president of the Ukraine in February after the raid on the gas company president’s house," Graham said on Wednesday during an appearance on Fox News.

Biden and Graham are considered to be friends and worked together on several bipartisan issues during Biden's time in the Senate.

"I am disappointed. Quite frankly, I'm angered," Biden said of Graham's request during a CNN interview that will air Friday night. "He knows me. He knows my son. He knows there's nothing to this. Trump is now essentially holding power over him that even the Ukrainians wouldn't yield to. Ukrainians would not yield to, quote, 'investigate Biden — there's nothing to investigate about Biden or his son.'"

He added. "Lindsey is about to go down in a way that I think he’s going to regret his whole life."

When asked what he would say to the South Carolina Republican, Biden said, "I say, 'Lindsey, I just — I'm just embarrassed by what you're doing, for you.' I mean, my lord."