WATCH: During hearing, Lewandowski calls Trump probes ‘petty’ politics

House Judiciary Committee Chairman Jerrold Nadler says former Trump campaign manager Corey Lewandowski “remains obligated” to answer the committee’s questions despite a White House order that he not discuss his confidential conversations with the president.

Lewandowski is testifying at the committee’s first official hearing in what the panel is calling an impeachment investigation. The White House sent Nadler a letter late Monday saying that Lewandowski was not allowed to discuss his conversations with President Donald Trump beyond what is already public in former special counsel Robert Mueller’s report.

READ MORE: WATCH LIVE: Corey Lewandowski testifies before Congress
Lewandowski is charging that House Democrats are “going down rabbit holes” and “focusing on petty and personal politics” as he is testifying at what the committee is calling its first impeachment hearing.

Lewandowski says that investigations of President Donald Trump have been “populated by many Trump haters who had their own agenda — to take down a duly elected President of the United States.”

House Democrats have called in Lewandowski to testify about former special counsel Robert Mueller’s report. Mueller’s investigators detailed episodes in which Trump asked Lewandowski to direct then-Attorney General Jeff Sessions to limit Mueller’s investigation. Mueller said he could not exonerate Trump on obstruction of justice.

Lewandowski said there’s been “harassment of the president from the day he won the election.”