President Donald Trump repeatedly prodded Ukraine's new leader to work with lawyer Rudy Giuliani and the US attorney general to investigate Democratic political rival Joe Biden, according to a memo summarising a July 25 call that was released Wednesday.
A five-page summary of the call detailed a conversation between Trump and Ukrainian President Volodymyr Zelenskiy.
It's just one piece of an overall complaint made in mid-August by a whistle-blower. The complaint is central to the formal impeachment inquiry launched Tuesday by Democratic House Speaker Nancy Pelosi.
Trump has denied any wrongdoing, and called the impeachment inquiry "witch-hunt garbage".
Here's a look at what the call summary tells us - and what it doesn't.
What we know
Trump told the Ukrainian president, "If you can look into it ... it sounds horrible to me," referring to unsubstantiated allegations that Biden sought to interfere with a Ukrainian prosecutor's investigation of his son Hunter, who had been hired by a gas company in that country.
"There's a lot of talk about Biden's son, that Biden stopped the prosecution and a lot of people want to find out about that, so whatever you can do with the attorney general would be great," Trump said in the call, according to the summary provided by the Justice Department.
"Biden went around bragging that he stopped the prosecution so if you can look into it. ... It sounds horrible to me," Trump said, according to the memo.
There has been no evidence of wrongdoing on the part of Biden or his son.
The memo also said that Trump told Zelensky that Attorney General William Barr, the top US law enforcement official, would reach out to him about re-opening the investigation into the Ukrainian gas company.
The connection to Barr marked a new and potentially more serious issue for Trump because it shows he took steps to involve the US government with a foreign country to investigate a political rival.
Trump did not ask Barr to contact Ukraine, Justice Department spokeswoman Kerri Kupec said, and Barr has not communicated with Ukraine about a possible investigation or any other subject. Barr, a Trump appointee, first found out about the conversation several weeks after it took place, Kupec said.
Separate to the memo, Trump also confirmed that he ordered his staff to freeze nearly $400m in aid to Ukraine a few days before the call.
The Republican president has denied any wrongdoing.
What we don't know
The rough transcript is not a full account of what was said on the call between Trump and Zelenskiy - meaning more details might yet emerge.
Congress has also not seen the full whistle-blower's complaint, which is believed to be based on more than just the call.
The US Senate voted unanimously on Tuesday, with no objections from Trump's fellow Republicans, for a resolution calling for the whistle-blower's report to be sent to Congress. The House is due to vote on a similar non-binding resolution on Wednesday.
In the meantime, the impeachment probe focuses partly on whether Trump abused his presidential powers and sought help from a foreign government to undermine Biden and help his own reelection effort.
Whether Trump's comments in the partial transcript rise to that will ultimately be up to the Democrat-controlled House, which can eventually vote to move forward with impeachment proceedings.