– Democrats' first impeachment hearing quickly turned hostile Tuesday as their sole witness, former Trump campaign manager Corey Lewandowski, stonewalled many questions and said they were "focusing on petty and personal politics."

Lewandowski, a devoted supporter of President Donald Trump, was following White House orders not to discuss conversations with Trump beyond what was already public in the Mueller report. Trump was cheering him along as he testified, tweeting that his opening statement was "beautiful."

The hearing underscores what has been a central dilemma for House Democrats all year as they try to investigate — and potentially impeach — Trump. Many of the Democrats' base supporters want them to move quickly to try to remove Trump from office. But the White House has blocked their oversight requests at most every turn, declining to provide new documents or allow former aides to testify.

On Tuesday, Lewandowski made clear he wouldn't make life easy for the Democrats. He demanded that they provide him a copy of the Mueller report, sending Democratic staff scrambling to find one. He then read directly from the report, showing that he wouldn't say much beyond what special counsel Robert Mueller wrote. Republicans then forced a series of procedural votes, immediately sending the hearing into disarray.

"He's filibustering," said House Judiciary Committee Chairman Jerrold Nadler.

Lewandowski eventually began to answer some questions — he told the committee that he doesn't think "the president asked me to do anything illegal" — but still stuck mostly to the report, giving Democrats little new information. And he made clear his dislike for the House majority in the opening statement, calling them petty and asserting that investigations of the president were conducted by "Trump haters."

Democrats say the White House blockade and stonewalling witnesses like Lewandowski just gives them more fodder for lawsuits they have filed against the administration — and possible articles of impeachment on obstruction.

Two other witnesses who were subpoenaed alongside Lewandowski, former White House aides Rick Dearborn and Rob Porter, didn't show up, on orders from the White House. "This is a cover-up plain and simple," Nadler said. "If it were to prevail — especially while the Judiciary Committee is considering whether to recommend articles of impeachment — it would upend the separation of powers as envisioned by our founders."

The GOP Senate is certain to rebuff any House efforts to bring charges against the president. And moderate Democrats in their own caucus have expressed nervousness that the impeachment push could crowd out their other accomplishments.

Still, the Judiciary panel is moving ahead, approving rules for impeachment hearings last week. Among those guidelines is allowing staff to question witnesses.

Tuesday's hearing alternated between combative exchanges between Lewandowski and Democrats and friendly questions from the Republicans. "They are going to bring back anybody, as much as they have to, to find something, anything to keep impeachment hopes alive," Rep. John Ratcliffe, R-Texas, told Lewandowski.

He was a central figure in Mueller's report. Mueller's investigators detailed two episodes in which Trump asked Lewandowski to direct Attorney General Jeff Sessions to limit Mueller's investigation. Trump said that if Sessions would not meet with Lewandowski, then he should tell Sessions he was fired.

Lewandowski never delivered the message but asked Dearborn, a former Sessions aide, to do it. Dearborn said he was uncomfortable with the request and declined to deliver it, according to the report.

Under questioning by Rep. Hank Johnson, D-Ga., Lewandowski confirmed as "accurate" that Trump had asked him to deliver the message. At least two Democrats asked if he "chickened out." Lewandowski said no — he took his kids to the beach instead.