U.S. President Donald Trump acknowledged Sunday that he had discussed Democratic presidential hopeful Joe Biden and his son in a call with Ukraine's president.

Trump's statement to reporters about his July 25 call with Ukrainian President Volodymyr Zelensky came as the Democratic leader of a key congressional panel said the pursuit of Trump's impeachment may be the "only remedy" to the situation.

Trump's call with Zelensky has been at the center of an escalating scandal in Washington since Friday, when news outlets reported that Trump had repeatedly asked the Ukrainian leader to investigate whether Biden — the Democratic front-runner to take Trump on in next year's election — misused his position while vice president.