"Again, the President of Ukraine said there was NO (ZERO) PRESSURE PUT ON HIM BY ME. Case closed!" Trump posted Monday, the last day of his record-setting month. US President Donald Trump speaks during news conference with Finnish President Sauli Niinisto in the East Room of the White House. Credit:AP The president and the White House are scrambling to push back on the fast-moving Ukraine scandal that could upend the rest of his first term and redefine the political landscape for his 2020 reelection bid. Trump insisted that his call with Ukrainian President Volodymyr Zelensky was appropriate. In more than 320 tweets and retweets since the story broke of a whistleblower report on Trump's phone call in July with Zelensky, Trump used or repeated the word "treason" five times and the word "Ukraine" more than four dozen times. In two dozen instances, Trump raised the name of Biden or his son Hunter, who had once worked in Ukraine.

Trump told the Ukrainian president there was "a lot of talk" about Biden's son's activities in Ukraine and he would direct his personal attorney Rudy Giuliani and Attorney General William Barr to assist in the inquiry "to get to the bottom of it." Trump's conversations with Ukrainian President Volodymyr Zelensky helped trigger an impeachment inquiry. Credit:AP House Speaker Nancy Pelosi launched an impeachment investigation last week into whether Trump abused his office for political gain. White House attorneys are preparing to respond to possible subpoenas from the House Intelligence Committee. Members of Trump's communications team respond to a steady stream of news stories about investigations into Trump's conduct with foreign leaders. Trump's reelection campaign put out ads accusing Democrats of trying to "steal" the 2020 election by lying about Trump.

Trump anger In appearances in the Oval Office and a joint press conference with the president of Finland on Wednesday in the US, Trump displayed an unusual show of anger as he defended what he has called his "perfect" phone call with Zelensky. US President Donald Trump speaks while Sauli Niinisto, Finland's president, smiles during a meeting at the Oval Office. Credit:Bloomberg He suggested, without evidence, that House intelligence committee chairman Adam Schiff may have committed treason, and, again without evidence, labelled Biden and his son "stone cold crooked". At one point, Trump demanded that a reporter pressing him on his dealings with Ukraine move on.

"Ask the president of Finland a question, please," he said, emphasising each word, eventually labelling the reporter "corrupt". Loading His outburst came hours after Democratic leaders in the House of Representatives warned the White House to expect a subpoena for documents. Democrats accused the administration of "flagrant disregard" of previous requests and said that refusal could be considered an impeachable offence. Democrats accused Trump of "an incitement to violence" against a national security whistleblower and advised him and his administration not to intimidate potential witnesses in the impeachment inquiry.

The whistleblower exposed a July phone call that Trump had with Ukrainian President Volodymyr Zelensky in which Trump pressed for an investigation of Democratic political rival Joe Biden and his family. Democrats say the pressure on Zelensky, on its own, constitutes an abuse of power worthy of impeachment scrutiny. 'Should be suspended' The president isn't the only administration official using Twitter. Tuesday, Secretary of State Mike Pompeo posted a letter he wrote to House Democrats blasting their investigation and suggesting he would fight their request to depose five State Department employees involved with Ukraine.

No administration official has used Twitter more than Trump, stepping up a practice he cultivated as a New York businessman, former reality TV star and 2016 presidential candidate. Like other Republicans, Trump tweeted denunciations of the impeachment inquiry as a politically motivated plot designed to hurt him in the 2020 election. Senator Kamala Harris, one of the Democratic presidential candidates, said on Tuesday that Trump has abused social media to a dangerous degree and should be suspended from its use. "The words of a president matter," Harris tweeted. "Trump has again shown he is irresponsible and endangering others with his tweets. He should lose the privilege to be on Twitter."

Judd Deere, a White House spokesman, said Trump's use of technology "to communicate directly with the American people should be praised, not criticised." Deere said that instead of "obsessing over how many times the president has tweeted," the media should instead cover his agenda. Experts said there are tangible benefits for Trump ramping up the frequency of his social media posts -- assuming people continue to tune in. The constant stream of tweets helps the president keep pace with the 24-hour cable news cycle. "If you see them frequently, you increase the likelihood that you think they're accurate," said Kathleen Hall Jamieson, director of the Annenberg Public Policy Centre at the University of Pennsylvania. Jamieson said she's surprised Trump has not tweeted more about the economy or unemployment, which has been a central message for the president heading into the 2020 reelection campaign. The president hasn't tweeted the word "unemployment" since the scandal broke, though he has mentioned "jobs" and the "economy" a handful of times.

"He's lost control of the agenda," Jamieson said. Instead, his focus has been on impeachment-related matters. Since Sept. 19, Trump has mentioned "Ukraine" or "Ukrainian" 56 times; "whistleblower" 25 times; "Biden" 24 times and "Schiff" 22 times, according to a USA TODAY analysis of data from the Trump Twitter Archive. "It's all about repetition," said Jennifer Grygiel, assistant professor of communication at Syracuse University who has written on presidential use of social media. Grygiel said more tweets help the president carry his message to supporters and around traditional media rather than prompting people to tune out. "It doesn't lose its effect, it carries more impact," Grygiel said.