“Desperate and defensive, Trump sends one crazed tweet after another — insinuating that the whistleblower should be executed, threatening to prosecute the chairman of the House Intelligence Committee, warning direly of civil war,” Biden said.

Biden also called Trump a “bully” and praises the “courageous” whistleblower who first brought the matter to light but whose identity, for now, remains unknown.

The vociferousness of Biden’s pushback against Trump also speaks to concerns by Democrats that the president’s attacks could have an effect on his candidacy.

The president and the Republican National Committee last week announced a $10 million ad buy, some of which will underwrite attack ads that advance an dubious claim that Biden, as vice president, pressured a prosecutor in Ukraine to drop an investigation into a natural gas company because it hired his son, Hunter Biden, in 2015 for consulting work.

Numerous Ukrainian officials and independent media reports have found no reliable evidence for Trump’s accusation that the investigation was ongoing at the time the prosecutor, Viktor Shokin, was pressured to quit or that Biden used improper pressure on behalf of his son. At that time, a coalition of Ukrainian and international groups was pushing for Shokin to be removed for corruption.

“He is repeatedly smearing me and my family. His party fans out to carry the smear. Millions of dollars in dishonest attack ads are blanketing the airwaves — paid for by the special interests so well served by his presidency,” Biden said in his remarks.