WASHINGTON - U.S. President Donald Trump is doubling down on his claims that the impeachment inquiry is another episode in his political opponents' long saga to block him from winning the election, and to overthrow his presidency.

A day after Democratic lawmakers concluded a second week of public testimony from White House officials and other administration officials, the president renewed his accusations against the Democrats in a nearly hour-long live phone interview with a Fox News Channel program.

While speaking with "Fox & Friends" hosts, Trump repeated old claims that Democrats targeted his campaign since the beginning, expressing suspicion that the White House under former President Barack Obama was involved in those attempts.

"You're dealing with the highest levels of government. They were spying on my campaign," said Trump.

The president has alleged in the past that the Obama White House tapped the phones of Trump campaign officials, without offering any evidence. The Justice Department is expected to issue a report on Dec. 9 investigating how the FBI's probe into Russian election meddling began.

Russia's meddling in the 2016 election remains a focus of the president, who has cast suspicion on the U.S. intelligence community's conclusions that Moscow alone was responsible. Instead, Trump continues to believe Ukraine was involved, and a Ukrainian company played a key role in holding a computer server with information from the presidential campaign of Hillary Clinton. He insisted in his interview Friday that he was pressing Ukrainian President Volodymyr Zelenskiy for information about that theory.

"They have the server. I still want to see that server, the FBI still hasn't got that server. A Ukrainian company got that server. That's what that call (with Zelenskiy) was about. We're looking for corruption. I asked him very point blank because we're looking for corruption," Trump said.

This week, Fiona Hill, a former senior White House national security official who is an expert on Russia, warned Republicans that repeating the debunked theory that Ukraine was behind election interference played into Russia's disinformation campaign.

"The unfortunate truth is that Russia was the foreign power that systematically attacked our democratic institutions in 2016," she said. "This is the public conclusion of our intelligence agencies, confirmed in bipartisan congressional reports. It is beyond dispute, even if some of the underlying details must remain classified."

Next steps

The impeachment inquiry has concluded two weeks of public testimony from several witnesses, including current and former White House officials, who have discussed allegations that the U.S. president abused his authority by pressuring a foreign leader to achieve personal political gains.

At the center of the investigation is the July 25 call when Trump asked Zelenskiy "to do us a favor" by investigating one of his chief 2020 Democratic rivals, former Vice President Joe Biden, as well as the debunked theory that Ukraine worked in 2016 to help Trump's Democratic challenger, former U.S. Secretary of State Hillary Clinton.

Democrats are expected to begin drafting articles of impeachment based on the testimony so far, and could vote on them before the end of the year.

Present and former administration officials, including the acting White House Chief of Staff Mick Mulvaney and former National Security Adviser John Bolton, could provide valuable testimony to the investigation. The House Democrats have requested that they testify, but both have filed for court rulings to determine if they have to comply.