Democratic calls to impeach President Donald Trump are gathering pace after it emerged he withheld aid to Ukraine, pressing it to investigate his would-be White House challenger Joe Biden.
The House of Representatives’ Democratic leader, Speaker Nancy Pelosi, is meeting party members on Tuesday to consider impeachment.
Mr Trump has acknowledged freezing the aid to Ukraine but denied wrongdoing.
Only two US presidents have ever been impeached.
What’s the latest on Ukraine?
At the United Nations General Assembly in New York City on Tuesday, Mr Trump said he only froze military aid to Ukraine because he wanted European countries to contribute money, too.
The Republican president also acknowledged pressuring newly elected Ukrainian President Volodymyr Zelensky during a phone call on 25 July to investigate US Democratic presidential candidate Joe Biden.
He told reporters “there was pressure put on, in respect to Joe Biden. What Joe Biden did for his son, that’s something they should be looking at”.
Mr Trump and his conservative allies have pointed out that Joe Biden, while US vice-president, threatened in 2016 to withhold aid to Ukraine unless it fired a top prosecutor whose office had opened an investigation into a natural gas company where his son, Hunter Biden, was a board member.
Other Western officials had also called for the same prosecutor to be removed on the grounds that he was soft on corruption. Ukraine’s current prosecutor, Yuriy Lutsenko, told Bloomberg News in May he had no evidence of wrongdoing by Mr Biden or his son.
Mr Trump’s latest remarks came after US media reported that days before his phone call with Mr Zelensky, Mr Trump instructed his acting chief of staff, Mick Mulvaney, to withhold nearly $400m (£320m) in military aid for Ukraine.
But the US president insisted on Tuesday that nothing untoward happened during the “perfect call”.
Later in the day, the US president told reporters: “Ask how his [Joe Biden’s] son made millions of dollars from Ukraine… even though he had no expertise whatsoever, OK.”
Congressional Democrats are demanding a transcript of the Trump-Zelensky phone call, which the White House has declined to release.
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What’s the latest on impeachment?
On Tuesday, Nancy Pelosi, the most powerful elected Democrat, is holding a closed-door meeting with House members to consider impeaching Mr Trump.
She has so far resisted calls among her liberal rank-and-file to attempt to remove the Republican president from office.
On Monday night, the Washington Post published an op-ed by seven Democratic lawmakers – all with backgrounds in the US military and intelligence agencies – who said the “stunning” accusations against Mr Trump amounted to “a national security threat”.
“If these allegations are true, we believe these actions represent an impeachable offence,” wrote the lawmakers. “We do not arrive at this conclusion lightly.”
The first-term representatives – Gil Cisneros of California, Chrissy Houlahan of Pennsylvania, Abigail Spanberger and Elaine Luria of Virginia, Jason Crow of Colorado, Mikie Sherrill of New Jersey and Elissa Slotkin of Michigan – all serve in districts previously held by Republicans.
Nearly a dozen Democrats have come out in favour of impeachment over the last week since the Ukraine phone call controversy came to light.
More than 145 House Democrats now back such a move – more than half of the party’s 235 members in the lower chamber of Congress.
But impeachment currently lacks the support of most US voters. A recent opinion poll found that 59% oppose removing the president from office.
Under the US Constitution, the House has the power to impeach a president for “high crimes and misdemeanours” and the Senate then holds a trial on whether to remove the president from office.
But the Senate is under Republican control and is seen as highly unlikely to convict the president.
Presidents Bill Clinton and Andrew Johnson were impeached, but the Senate did not convict them.
How is Biden responding?
Mr Biden – who has so far not joined calls for impeachment – will make a statement on Tuesday afternoon from his political heartland of Wilmington, Delaware.
His campaign said the statement would relate to the president’s “ongoing abuse of power”.
The Biden team has hit back aggressively at Mr Trump’s Ukraine allegations, denying any wrongdoing.
Mr Biden told reporters on Saturday: “Trump’s doing this because he knows I will beat him like a drum.”
He also raised his voice and jabbed his finger at a Fox News reporter, telling him: “Ask the right questions!”
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Trump Ukraine call: Democratic calls for impeachment grow