UPDATE - Trump says he ordered Ukraine aid withheld

ADDS DETAILS THROUGHOUT; TRUMP TWEET; PELOSI NEWS CONF. ANNOUNCEMENT

By Michael Hernandez

WASHINGTON (AA) - U.S. President Donald Trump acknowledged Tuesday he froze aid to Ukraine in the run-up to a telephone conversation with that country's president that has drawn scrutiny after a whistle-blower flagged the discussion for possible wrongdoing.

Trump continued to deny any wrongdoing, claiming he did not seek a "quid pro quo" from recently-seated President Volodymyr Zelensky in return for freeing up the blocked funding.

The president said he held up millions in military aid previously appropriated by Congress to get European nations to help fund the effort.

"Why is the United States the only one paying for Ukraine? And I’ve been talking abut this for a long time. Not only with respect to Ukraine but a lot of other countries,” Trump said during a meeting with UK Prime Minister Boris Johnson on the sidelines of the UN General Assembly. “Frankly why isn’t Germany - I just met with the chancellor - why isn’t Germany, why isn’t France, why aren’t those other countries paying? And why are we paying all the time? And nobody’s given, I believe, more to Ukraine."

Revelations of the whistle-blower complaint and ensuing claims that Trump sought to hold up the funding in an effort to have Zelensky probe former Vice President Joe Biden's son, Hunter, for possible corruption have prompted increasing calls for congressional Democrats to begin impeachment proceedings against the president.

Doing so potentially would be an improper use of his office that could be rise to the level of impeachable conduct.

Joe Biden was the point person for Ukraine during the Obama administration and sought to have the country crack down on corruption, which included his successful call for the ouster of a Ukrainian prosecutor, Viktor Shokin, which was supported at the time by the international community.

Shokin was reportedly probing Burisma Holdings, a natural gas company whose board the younger Biden joined in 2014, among other cases.

Joe Biden is the leading contender for the 2020 Democratic nomination and could potentially face off against Trump next November.

Trump has charged that Biden and his son are corrupt, but he has yet to lay out any evidence to support his claims. Trump's three eldest children -- Donald Trump, Jr., Eric and Ivanka -- are all involved in international business dealings while their father occupies the Oval Office.

Trump said later Tuesday he authorized the release of "the complete, fully declassified and unredacted transcript" of his call with Zelensky, vowing it will exonerate him.

"You will see it was a very friendly and totally appropriate call. No pressure and, unlike Joe Biden and his son, NO quid pro quo!" Trump wrote on Twitter. "This is nothing more than a continuation of the Greatest and most Destructive Witch Hunt of all time!"

The announcement comes as House Speaker Nancy Pelosi is expected to address reporters at 5 p.m. local time (2100GMT) after meeting with House chairmen and her wider caucus.

Biden has urged Trump to release the transcript, and said Tuesday he would support impeachment proceedings if the White House stonewalls congressional demands for information on the call.