Mr. Pompeo on Wednesday described United States policy toward Ukraine as “remarkably consistent,” being focused on addressing “the threat that Russia poses” and attempts at “helping the Ukrainians to get graft out, and corruption outside of their government.”

“Even,” he added, “while all this noise is going on.”

Current and former State Department officials have said it is unusual for a secretary of state to listen in on presidential calls with other world leaders. That is normally a role filled by the White House national security adviser and the National Security Council staff.

Mr. Pompeo supports a get-tough policy on Russia and may have been included on the call to ensure that message was reflected in Mr. Trump’s comments to the Ukrainian president.

John R. Bolton, another Russia hawk who then was serving as national security adviser, often disagreed with Mr. Pompeo, and they competed for Mr. Trump’s ear. Since Mr. Bolton was ousted last month, Mr. Pompeo’s influence has grown.

In his request to Mr. Zelensky, Mr. Trump pushed a conspiracy theory that his own staff had repeatedly told him was false — that Ukraine, not Russia, had intervened in the 2016 election and that it had done so on behalf of the Democrats.

In another call, to Prime Minister Scott Morrison of Australia, Mr. Trump asked for help discrediting the Mueller investigation into Russia’s election interference.

Mr. Trump has repeatedly vented his anger at the impeachment inquiry on Twitter, asking why he was not “entitled to interview” and know the identity of the whistle-blower, whose anonymity is protected by law to prevent retaliation. He has also tweeted that he is the target of an attempted coup and that Representative Adam B. Schiff, Democrat of California and the chairman of the Intelligence Committee, should be arrested.