The top U.S. diplomat in Ukraine told Congress on Tuesday that he believed President Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE tied Ukrainian aid to requests for politically motivated "investigations."

In the statement, made behind closed doors to three House committees, William Taylor described "an irregular, informal channel of U.S. policymaking with respect to Ukraine" that he called "separate and at odds" with his own "regular" diplomatic channel.

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"The push to make [Ukrainian President Volodymyr Zelensky] publicly commit to investigations of Burisma and alleged interference in the 2016 election showed how the official foreign policy of the United States was undercut by the irregular efforts led by [Trump's personal attorney Rudy Giuliani Rudy GiulianiThe Hill's Campaign Report: GOP set to ask SCOTUS to limit mail-in voting CIA found Putin 'probably directing' campaign against Biden: report Democrats fear Russia interference could spoil bid to retake Senate MORE]," Taylor said in the statement.

Burisma is the Ukrainian company Hunter Biden, the son of former Vice President Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE, formerly advised.

"I understood a 'stalemate' to mean that Ukraine would not receive the much-needed military assistance," Taylor added regarding U.S. efforts he described to pressure Zelensky to agree to such investigations.

Read Taylor's opening statement below.