Washington CNN  — 

President Donald Trump asked his acting chief of staff Mick Mulvaney to put a hold on millions in military aid to Ukraine roughly one week before a call with the Ukrainian president in which he pressured the country to investigate former Vice President Joe Biden’s son, two senior administration officials said on Monday.

Trump, who was in the middle of a broad review of foreign aid programs when he singled out Ukraine specifically this summer, was primarily concerned with “corruption” in Ukraine and Europe shouldering more of the financial burden for supporting Ukraine’s defense, according to one of the officials.

News of Trump’s order to withhold aid to the Ukraine ahead of his July 25 call may trigger questions – and speculation – about the President’s motive in doing so.

Trump had ordered a hold on nearly $400 million of military and security aid to Ukraine at least a week before the call in question, US officials familiar with the matter tell CNN. The Washington Post first reported the figure.

The administration was looking at harnessing multiple foreign packages, several aides believed, when Trump took a special interest in Ukraine, at times railing about how the country wasted money in his eyes. This surprised several staffers because, as CNN has reported, Trump had not been interested in engaging with Ukraine in the past, believing Ukraine was a corrupt country that wasn’t committed to reform.

But his attentiveness to the country had ramped up in recent weeks as his personal attorney Rudy Giuliani pushed muddled corruption accusations against Biden, who was leading in national polls against Trump, and his son Hunter.

There is no evidence of wrongdoing by either Joe or Hunter Biden.

On Friday, CNN reported Trump pressed Ukrainian President Volodymyr Zelensky in the call to investigate former Vice President Joe Biden’s son, Hunter, according to a person familiar with the situation. On the day of Trump’s call with Zelensky, word began to spread that Trump was reviewing a plan to cut foreign assistance to Ukraine.

That call was part of the whistleblower complaint submitted to the Intelligence Community Inspector General, another person familiar with the situation told CNN.

Trump on Sunday said that he did indeed discuss Biden with Ukraine’s president – at a time when the country was awaiting the aid package from the United States – but he denied doing anything improper.

Neither Trump nor his aides have given another reason why his administration singularly stalled the Ukrainian aid package for several weeks.

Citing three senior administration officials with knowledge of the internal deliberations, the Post said officials at the Office of Management and Budget passed along Trump’s request to the Pentagon and the State Department at an interagency meeting in mid-July.

According to the paper, administration officials were told to tell lawmakers that the delay in aid was the result of an “interagency process” without giving more information.

The growing controversy has brought House Democrats near a “tipping point” on impeachment as the party weighs how to respond to the incident. House Speaker Nancy Pelosi, who sharpened her rhetoric over the weekend, is still not committing to moving forward with impeachment proceedings – though she is keeping the door open.

This story has been updated with CNN reporting from two senior administration officials.

CNN’s Manu Raju and Kylie Atwood contributed to this report.