Corey Lewandowski, President Donald Trump's former campaign manager and close confidant, on Tuesday stoutly defended his former boss and lashed out at Democrats during testimony to a US congressional panel considering whether to impeach Trump. "We as a nation would be better served if elected officials like you concentrated your efforts to combat the true crises facing our country as opposed to going down rabbit holes like this hearing," Lewandowski said in his written opening remarks to the Democratic-led House of Representatives Judiciary Committee released ahead of the hearing. The White House on Monday told Lewandowski not to discuss conversations he had with Trump after he became president including an exchange that Democrats view as evidence that Trump committed obstruction of justice by trying to interfere in a federal investigation and may need to be impeached. Lewandowski was the first impeachment witness to appear before the committee since former Special Counsel Robert Mueller testified in July about his inquiry that detailed Russian 2016 election interference and Trump's actions to impede the investigation. Lewandowski said in his testimony he did recall ever having any conversations with "foreign entities" offering help to manipulate the outcome of the election. The hearing appeared likely to produce more political theater than factual revelations. Lewandowski assailed the federal investigation into Russian interference in the 2020 election. "It is now clear the investigation was populated by many Trump haters who had their own agenda - to try and take down a duly elected president of the United States. As for actual 'collusion' or 'conspiracy,' there was none. What there has been however, is harassment of the president from the day he won the election," Lewandowski added. Lewandowski is considering a run for the US Senate as a Republican in New Hampshire. Mueller's report described Lewandowski as a Trump "devotee" with a "close" relationship with the president. Trump in August sought to boost Lewandowski's potential Senate bid, calling his former aide "a fantastic guy" who would make a "great senator" and that "I like everything about him." "This isn't a campaign rally. This is the first hearing where you can tell the American people how you participated in the president's effort to obstruct justice," Democratic Representative David Cicilline wrote on Twitter. Democrats, who hope to decide whether to recommend Trump's impeachment to the full House by year's end, had intended to grill Lewandowski about the president's effort to persuade then-Attorney General Jeff Sessions to redirect the Mueller probe away from the 2016 Trump election campaign. The episode is among a number of incidents contained in Mueller's 448-page investigative report made public in April that Democrats view as evidence that Trump obstructed justice. Mueller made no determination about whether Trump obstructed justice but did not exonerate him of wrongdoing. Under the US Constitution, the House has the power to vote to impeach a president while the Senate then would hold a trial on whether to remove him from office. The House is controlled by Democrats and the Senate by Trump's fellow Republicans. White House Counsel Pat Cipollone told the committee in a letter on Monday that Lewandowski could not testify about conversations with Trump after he became president or with his senior advisers. The White House also directed two other witnesses, former Trump White House aides Rob Porter and Rick Dearborn, not to testify. Cipollone's letter said they were "absolutely immune from compelled congressional testimony with respect to matters related to their service as senior advisers to the President." "Mr. Lewandowski will testify before Congress regarding matters already made public in the Mueller report. Any information about his communications with the president or with senior advisers to the president not already disclosed in the Mueller report, however, remains confidential," White House spokesman Steven Groves said in a statement. The Judiciary Committee's chairman, Democrat Jerrold Nadler, called the White House move a "shocking and dangerous assertion of executive privilege and absolute immunity." "If he were to prevail in this cover-up while the Judiciary Committee is considering whether to recommend articles of impeachment, he would upend the separation of powers as envisioned by our founders," Nadler said in a statement, referring to Trump. In June 2017, Trump met Lewandowski, then a private citizen, at the White House and dictated a message he was to deliver to Sessions. The message said Sessions should shift the Russia probe's focus to future elections despite his recusal from the investigation. At a second meeting a month later, Trump asked about the status of the message and said Lewandowski should "tell Sessions he was fired" if he would not meet with Lewandowski, according to the Mueller report. Trump fired Lewandowski as his campaign manager in June 2016 but the two remained close. During the campaign, Lewandowski had often generated controversy including when he was charged with misdemeanor battery after being accused of forcefully grabbing a female reporter in Florida. The charge was later dropped. — Reuters