WASHINGTON, D.C. — House of Representatives Speaker Nancy Pelosi (D-CA) said on Thursday President Trump already has admitted to bribery in the Ukraine scandal at the heart of a Democratic-led inquiry accusing him of an impeachable offense under the U.S. Constitution.

“The bribe is to grant or withhold military assistance in return for a public statement of a fake investigation into the elections. That’s bribery,” Pelosi, the top Democrat in Congress, told a news conference the day after the first public hearing in the impeachment inquiry she announced in September.

“What the president has admitted to and says it’s ‘perfect,’ I say it’s perfectly wrong,” Pelosi said. “It’s bribery.”

Democrats are looking into whether the Republican president abused his power by withholding $391 million in U.S. security aid to Ukraine as leverage to pressure Kiev to conduct two investigations that would benefit him politically. The money, approved by Congress to help a U.S. ally combat Russia-backed separatists in the eastern part of the country, was later provided to Ukraine.

Trump has denied any wrongdoing.

Another central figure — former U.S. Ambassador to Ukraine Marie Yovanovitch — is due to testify on Friday in the second public hearing in the inquiry.

The inquiry threatens Trump’s presidency even as he seeks re-election in November 2020. If the House approves articles of impeachment — formal charges — against Trump, the Senate would then hold a trial on whether to convict him and remove him from office. Republicans control the Senate and have shown little support for Trump’s removal.

Pelosi’s comments could offer a preview of articles of impeachment Democrats might put forward. At her news conference, she also said Trump’s administration had committed “obstruction of Congress” by blocking testimony of officials summoned to testify in the inquiry.

The Constitution states that impeachable offenses include “treason, bribery or other high crimes and misdemeanors.” Democrats have begun to use the words bribery or attempted bribery in discussing Trump’s actions. According to precedent, obstruction could be another article of impeachment.

Republicans have said House Democrats already have decided to pass articles of impeachment, but Pelosi denied that was the case, saying the inquiry must play out before any decision can be made.

The focus of the inquiry is a July 25 phone call in which Trump asked Ukrainian President Volodymyr Zelenskiy to investigate Democratic rival Joe Biden and the former vice president’s son Hunter, who had served as a board member of a Ukrainian energy company called Burisma. Trump also asked Zelenskiy to investigate a debunked conspiracy theory embraced by some Trump allies that Ukraine, not Russia, interfered in the 2016 U.S. election.

Pelosi compared Trump’s actions with former President Richard Nixon’s conduct in the Watergate corruption scandal that led him in 1974 to become the only U.S. president to resign. Pelosi said Trump’s actions to enlist a foreign power to help him in a U.S. election and the obstruction of information about that — she called it a cover-up — “makes what Nixon did look almost small.”

Democrats are aiming to settle the question of Trump’s impeachment before the end of the year.