Trump slams 'partisan' whistleblower, Biden pushes back

US President Donald Trump on Friday vigorously rejected a whistleblower's claim of wrongdoing, amid reports he used a call with Ukraine's president to pressure him to investigate the son of Trump's Democratic rival Joe Biden.

The whistleblower's secret complaint has triggered a tense showdown between Congress, whose Democratic leaders are demanding to review the complaint, and the executive branch which has barred them from doing so.

It has also raised concerns Trump sought to strong-arm Ukraine into providing damaging information on the president's possible 2020 challenger, which would represent dangerous foreign meddling in the US election -- similar to the interference blamed on Russia in 2016, when Trump defeated Hillary Clinton.

The Washington Post, citing two unnamed former US officials, said the complaint stemmed from Trump's communications with Ukraine, and a "promise" allegedly made by the president.

Trump slammed the "ridiculous" story, attacking the "partisan whistleblower," despite admitting to not knowing the person's identity.

He insisted he had a "totally appropriate" conversation, without detailing with whom, or what was said, and instead suggested Biden and his son should be investigated for their actions in Ukraine.

Biden responded forcefully, demanding Trump immediately release the transcript of the call and saying the reports Trump sought to coerce his Ukrainian counterpart, if true, amounted to "clear-cut corruption."
Biden -- who leads Trump according to most polls -- said the reports show the president's "willingness to abuse his power and abase our country."
The scandal has set Washington on edge, with House Speaker Nancy Pelosi saying the whistleblower complaint raises "grave, urgent concerns for our national security."