WASHINGTON — A former White House Russia analyst on Thursday denounced as “fictional” the contention from some Republicans that Ukraine interfered in the 2016 election and warned lawmakers not to advance a politically motivated narrative helpful to Russia as they defend President Donald Trump in the impeachment probe.

“I would ask that you please not promote politically driven falsehoods that so clearly advance Russian interests,” says Fiona Hill in prepared opening remarks to the House intelligence committee.

Hill was an aide to former national security adviser John Bolton and stressed that she is “nonpartisan” and has worked under Republican and Democratic presidents.

“I have no interest in advancing the outcome of your inquiry in any particular direction, except toward the truth,” Hill said.

But she said the conclusion by U.S. intelligence agencies that Russia meddled in the election “is beyond dispute.”

She said the assertion by some Republicans that Ukraine interfered in the election “is a fictional narrative that has been perpetrated and propagated by the Russian security services themselves.”

“I refuse to be part of an effort to legitimize an alternative narrative that the Ukrainian government is a U.S. adversary, and that Ukraine — not Russia — attacked us in 2016,” she said.

Some Republicans have advanced the Ukraine election interference talking point as they seek to defend Trump from allegations that he pressed Ukraine’s president to investigate Democrats and rival Joe Biden as he was withholding military aide.

They, and Trump himself, have said he was trying to root out corruption in the country.

Hill said U.S. support for Ukraine, “which continues to face armed Russian aggression, has been politicized.”

Hill is one of two key witnesses House impeachment investigators will hear on Thursday, capping an intense week in the historic inquiry. Both Hill and David Holmes, a political counselor at the U.S. Embassy in Kyiv, grew alarmed by how President Donald Trump and others in his orbit were conducting foreign policy in Ukraine.

Holmes says he was having lunch with Ambassador Gordon Sondland this summer when he overheard Trump on the phone asking the envoy about the investigations he wanted from the Ukraine president. The colorful exchange was like nothing he had ever seen, Holmes said in an earlier closed-door deposition.

Hill has said Bolton cut short a meeting with visiting Ukrainians at the White House when Sondland started asking them about “investigations.”

The impeachment inquiry focuses on allegations that Trump sought investigations of Biden and his son — and the discredited idea that Ukraine rather than Russia interfered in the 2016 U.S. election — in return for the badly needed military aid and a White House visit the new Ukrainian president wanted to show his backing from the West.

Those testifying publicly previously appeared for private depositions, most having received subpoenas compelling their testimony.

Holmes, speaking about the July 26 call between Trump and Sondland, has told investigators the call he overheard “was so remarkable that I remember it vividly.”

He said he heard Trump ask, “So he’s going to do the investigation?” According to Holmes, Sondland replied that Ukrainian President Volodymyr Zelenskiy “will, quote, ‘do anything you ask him to.’”

Hill said Bolton told her he didn’t want to be involved in any “drug deal” Sondland and Trump’s acting White House chief of staff Mick Mulvaney were cooking up over the Ukrainian investigations Trump wanted.

Sondland, a wealthy hotelier and donor to Trump’s inauguration, appeared before lawmakers Wednesday in a marathon session.

He declared that Trump and his lawyer Rudy Giuliani explicitly sought a “quid pro quo” with Ukraine, leveraging an Oval Office visit for political investigations of Democrats. But he also came to believe the trade involved much more.

Sondland testified it was his understanding the president was holding up nearly $400 million in military aid, which Ukraine badly needs with an aggressive Russia on its border, in exchange for the country’s announcement of the investigations.

Sondland conceded that Trump never told him directly the security assistance was blocked for the probes, a gap in his account that Republicans and the White House seized on as evidence the president did nothing wrong. But the ambassador said his dealings with Giuliani, as well as administration officials, left him with the clear understanding of what was at stake.

“Was there a ‘quid pro quo’?” Sondland testified in opening remarks. “With regard to the requested White House call and White House meeting, the answer is yes.”

The rest, he said, was obvious: “Two plus two equals four.”

In often-stunning testimony, he painted a picture of a Ukraine pressure campaign that was prompted by Trump himself, orchestrated by Giuliani and well-known to other senior officials, including Secretary of State Mike Pompeo. Sondland said he raised his concerns about a quid pro quo for military aid with Vice President Mike Pence — a conversation Pence said he didn’t recall.

However, Sondland said: “Everyone was in the loop. It was no secret.”

Later Wednesday, another witness undercut a main Republican argument — that Ukraine didn’t even realize the money was being held up. The Defense Department’s Laura Cooper testified that Ukrainian officials started asking about it on July 25, which was the day of Trump’s phone call with Zelenskiy, when he first asked for a “favor.”

Trump himself insists daily that he did nothing wrong and the Democrats are just trying to drum him out of office. On Wednesday, reading from notes written with a black marker, Trump quoted Sondland quoting Trump to say the president wanted nothing from the Ukrainians and did not seek a quid pro quo. He also distanced himself from his hand-picked ambassador, saying he didn’t know him “very well.”

Trump concluded, "It's all over" for the impeachment proceedings.

In Moscow on Wednesday, Russian President Vladimir Putin said he was pleased that the “political battles” in Washington had overtaken the Russia allegations, which are supported by the U.S. intelligence agencies.

"Thank God,” Putin said, “no one is accusing us of interfering in the U.S. elections anymore. Now they’re accusing Ukraine."

Associated Press writers Colleen Long, Laurie Kellman, Zeke Miller, Matthew Daly and Andrew Taylor contributed to this report.