Hours after U.S. President Donald Trump described him as "stone-cold crooked," Joe Biden, a leading Democratic contender in the 2020 race for the White House, vowed on Wednesday the Republican president is "not going to destroy me.""Let me make something clear to Trump and his hatchet men and the special interests funding his attacks against me," Biden said in prepared remarks distributed by his campaign in advance of an appearance in Reno, Nevada, on Wednesday night. "I’m not going anywhere. You’re not going to destroy me. And you’re not going to destroy my family. I don’t care how much money you spend or how dirty the attacks get," said Biden, who leads in most opinion polls among the 19 Democrats seeking their party's nomination to face Trump in next year's election.The back-and-forth came as Trump, first in a series of tweets and then at a news conference, angrily denounced an impeachment inquiry concerning a July call in which Trump asked Ukraine's president to investigate Biden and his son Hunter, who served on the board of a Ukrainian company while his father was vice president.Democrats have accused Trump of pressuring a vulnerable U.S. ally to meddle in the 2020 election for his own political benefit.On Wednesday, Trump insisted that he had acted appropriately, and called Biden and his son “stone-cold crooked.” The president has repeatedly accused the pair of wrongdoing without providing any evidence.Biden, in return, accused Trump of abuse of power in a statement sent to reporters before his speech on Wednesday.His campaign said Biden intended at the Reno event to portray Trump as a frightened bully."He did it because, like every bully in history — he’s afraid," Biden planned to say of Trump's accusations against him and his son. "He’s afraid of just how badly I would beat him next November."