A bipartisan group of lawmakers echoed then-Vice President Joe Biden s push for anti-corruption reforms in Ukraine, including within the countrys office of the prosecutor general, according to a 2016 letter unearthed by CNN .

In the letter , Sens. Rob Portman (R-Ohio) and Dick Durbin (D-Ill.), co-chairs of the bipartisan Senate Ukraine Caucus, pressed Ukraines then-President Petro Poroshenko to take action on entrenched corruption within his government.

We recognize that your governing coalition faces not only endemic corruption left from decades of mismanagement and cronyism, but also an illegal armed seizure of territory by Russia and its proxies, they wrote in the letter. [We] urge you to press ahead with urgent reforms to the Prosecutor Generals office and judiciary.

The letter also signed by Sens. Ron Johnson (R-Wis.), Mark Kirk (R-Ill.), Chris Murphy (D-Conn.), Jeanne Shaheen (D-N.H.), Richard Blumenthal (D-Conn.) and Sherrod Brown (D-Ohio) appears to undermine President Donald Trump s unsubstantiated claim that there was quid pro quo when then-Vice President Biden withheld aid to Ukraine to push the countrys leaders to fire its prosecutor general, Viktor Shokin.

Trump claims Biden did so for the purpose of impeding an investigation into Burisma, a Ukrainian gas company upon whose board Hunter Biden served. No evidence has been brought to light to suggest this.