KIEV (Reuters) - Ukraine is the unwitting participant in a political battle in Washington between President Donald Trump and the Democrats ahead of the 2020 election.

A view shows the U.S. embassy in Kiev, Ukraine September 25, 2019. REUTERS/Valentyn Ogirenko

Democrats launched an inquiry to impeach Trump over allegations he pressed Ukrainian President Volodymyr Zelenskiy to help smear Joe Biden, the frontrunner in the race to challenge Trump as the Democratic Party nominee next year.

Trump and Zelenskiy spoke by phone on July 25, and the White House has released a reconstruction of their conversation, in which Trump asks Zelenskiy to investigate the Biden family, and Zelenskiy agrees to do so.

Earlier, Trump had frozen nearly $400 million of aid to Ukraine. His critics accuse him of using the funds as leverage to pressure Zelenskiy into pursuing the investigation.

Zelenskiy denies being put under pressure and Trump dismissed the inquiry as a “witch hunt”.

WHAT ARE TRUMP’S ACCUSATIONS AGAINST BIDEN?

Biden was vice president in President Barack Obama’s administration and the point person for Ukraine. Trump alleges that Biden bullied the Ukrainian authorities to fire General Prosecutor Viktor Shokin in 2016, threatening to withhold $1 billion in loan guarantees if Kiev failed to comply.

According to Trump, Biden had Shokin fired because he was investigating the activities of Biden’s son Hunter, who was working for a Ukrainian gas company called Burisma.

Hunter Biden denies any wrongdoing during his work for Burisma. Joe Biden denies trying to protect his son, and says pressure to fire Shokin was being applied widely by European governments at the time because of concern over corruption.

Burisma was founded by a former minister and member of ex-President Viktor Yanukovich’s party. After the Kremlin-friendly Yanukovich was ousted following street protests in 2014, prosecutors opened a criminal probe into Burisma.

WHAT ELSE DOES TRUMP SAY ABOUT UKRAINE?

Trump’s personal attorney Rudolph Giuliani also alleges some officials in Ukraine conspired to help Trump’s Democratic challenger Hillary Clinton in 2016 by leaking information damaging to Trump’s then-campaign manager, Paul Manafort.

Manafort, a long-time Republican political consultant who is now serving a sentence after being convicted of fraud, had worked in Ukraine for Yanukovich for years before being hired by Trump.

Giuliani has singled out Serhiy Leshchenko, a former lawmaker who published details of off-the-books payments made by Yanukovich to Manafort.

HOW DID GIULIANI APPROACH ZELENSKIY?

A former comedian with no prior political experience, Zelenskiy won a landslide election victory in April. Before Zelenskiy was inaugurated, Giuliani announced in May that he would visit Ukraine, but then abruptly canceled his visit saying Zelenskiy was surrounded by Trump’s enemies. He named Leshchenko, who had been an advisor to Zelenskiy during his campaign.

After Giuliani canceled the trip, Andriy Yermak, an aide to Zelenskiy, sought to meet Giuliani on what Yermak said was his own initiative.

HOW WAS SHOKIN’S SACKING VIEWED AT THE TIME?

Shokin became General Prosecutor in February 2015 at a time when Ukraine’s Western backers were calling for Kiev to tackle corruption in exchange for billions of dollars in aid. Diplomats, anti-corruption activists and some officials accused Shokin’s office of blocking reform and stalling investigations.

Shokin’s critics included his deputy, Vitaliy Kasko, who publicly resigned in February 2016 saying the General Prosecutor’s office was a “brake on the reform of criminal justice, a hotbed of corruption”. Shokin’s office dismissed the resignation as a stunt.

The U.S. Ambassador at the time, Geoffrey Pyatt, in a September 2015 speech, singled out Shokin’s office as an obstacle to fighting corruption “by openly and aggressively undermining reform”.

While Trump calls Shokin a “tough prosecutor” and Giuliani asserts that Shokin was fired for investigating Burisma, Pyatt accused Shokin’s office of deliberately undermining a probe into Burisma’s founder both in Ukraine and in Great Britain.

Shokin was pushed out in March 2016, a decision publicly endorsed by the European Union. In 2017, Burisma said all investigations against the company and its founder were closed.

HAS UKRAINE BEEN INVESTIGATING HUNTER BIDEN?

Shokin and Shokin’s successor, Yuriy Lutsenko, both spoke to The Hill newspaper in Washington in articles published in March and April of this year. Shokin said before he was fired he had made “specific plans” for an investigation that “included interrogations and other crime-investigation procedures into all members of the executive board, including Hunter Biden.”

Lutsenko said he had begun looking into Burisma and Biden’s activities in connection to it. However, Lutsenko told Reuters last week there was no evidence of wrongdoing on the part of Biden’s son in his relationship with the energy firm.

According to the White House summary of Zelenskiy’s phone call with Trump, Zelenskiy assured Trump that his next prosecutor general, the man who replaced Lutsenko, “will be 100% my person” and “will look into the situation.”

WHAT ABOUT THE U.S. AMBASSADOR?

Pyatt’s successor as U.S. ambassador to Ukraine was Marie Yovanovitch, a career diplomat who had previously served as ambassador to other ex-Soviet republics. She returned home in May. Trump strongly criticized her in his phone call to Zelenskiy, and Zelenskiy agreed with Trump’s criticism.

Lutsenko has alleged that Yovanovitch had given him a list of people not to prosecute. The State Department called the allegation “an outright fabrication”. Trump’s son called her a “joker” while Giuliani accuses her of colluding on Clinton’s behalf. Yovanovitch left her post after what Democrats called a “political hit job”.