Biden’s clarion call for impeachment is part of a gradual escalation of taking on Trump directly. In his two prior speeches on the topic after news broke Sept. 20 that Trump may have improperly pressured Ukraine to investigate the Bidens, Biden was more circumspect and mentioned impeachment but didn’t directly say Trump should be impeached.

On Wednesday, Trump responded quickly on Twitter to Biden.

“So pathetic to see Sleepy Joe Biden, who with his son, Hunter, and to the detriment of the American Taxpayer, has ripped off at least two countries for millions of dollars, calling for my impeachment — and I did nothing wrong,” Trump wrote. “Joe’s Failing Campaign gave him no other choice!”

Trump also tweeted a video of a new attack ad against Biden that’s less misleading than a prior TV spot that some cable news companies refused to air as a result.

The new ad points out that Biden, as vice president, withheld U.S. aid from Ukraine in 2014 in accordance with U.S. policy as long as the nation did not fire its prosecutor, Viktor Shokin. Shokin recently signed an affidavit claiming he was fired because he was leading a corruption probe into a Ukrainian natural gas company, Burisma, that had hired Hunter Biden.

Unmentioned by the ad: Shokin was widely viewed as corrupt by multiple governments — including the U.S. — and his investigation into Burisma company had, according to other Ukrainian officials, stalled long before the gas company hired Biden’s son. Also, Shokin’s affidavit was filed in an unrelated court case brought by lawyers supporting Trump in a case involving his convicted former campaign manager.

Biden didn’t get into all of those details in his Wednesday speech as he laid out a case asserting that Trump is a well-known liar. He then turned to the president’s accusations against himself and his son Hunter, saying Trump had asked the president of Ukraine to probe his son’s business dealings in the country because he badly feared facing Biden in a general election. Biden defended his son, saying news reports had independently knocked down allegations of wrongdoing.

“There’s no truth in his charges against me or my son — zero,” the former vice president said.

Biden also defended his own role in the firing of the former Ukraine prosecutor, saying he did it with the backing of the United States and its allies.

Biden laid out a case that Trump’s actions were unprecedented for a U.S. president, including calling for “civil war,” suggesting that a whistleblower had committed treason, and for obstructing the House’s impeachment investigation.

“He believes the entire U.S. government can be corrupted to further his personal, political needs,” Biden said.

Biden received a measure of unexpected cover Wednesday from the conservative journalist who laid the foundations for the attack against Hunter Biden for his Ukrainian and Chinese contracts wrote a New York Times op-ed that indicated no laws were broken.

“What Hunter Biden Did Was Legal — And That’s the Problem,” read the headline of the op-ed written by Pete Schweizer.

Democrats pushed back against the piece by pointing out Schweizer failed to mention how President Trump’s daughter, Ivanka Trump, received trademark approvals from China at the same time her father was negotiating trade deals with the country.

Initially, Biden met Trump’s attacks on his son with a measured response in two speeches.

In his first speech days after the Ukraine news broke, Biden on Sept. 24 only said the word “impeachment” once and said it should be used if the president obstructs an investigation.

“I’m going to let Congress do its job on impeachment,” Biden said in his second speech on the topic Oct. 2 . “And I’m going to stay focused on your lives.”

To that end, Biden’s campaign made sure to stay focused on policy initiatives, releasing proposals concerning gun control and education, without focusing too much on impeachment.

But the drumbeat within the Democratic Party for impeachment has grown louder in recent weeks as more details surrounding the president’s calls for several foreign nations to investigate a potential rival have emerged.

On Wednesday, the crowd of about 100 people was subdued when Biden first took the stage. But it livened up at Biden’s mocking of Trump as a well-known liar and Biden’s jeers at Rudy Giuliani, the president’s personal attorney who has given rambling and conspiratorial interviews that have even embarrassed some of Trump’s closest supporters.

When Biden snidely remarked that Giuliani was a man of great “integrity,” people in the room loudly laughed and cheered. Biden again had the room laughing when he poked at Trump for refusing to release his taxes. Biden then turned more serious.

“Where are his taxes?” Biden said again to big applause, noting he had released 21 years of his taxes. “What’s he hiding? What’s he afraid of? What’s buried in those returns?”