Joe Biden's campaign issued a memo to reporters that outlined a new strategy for dealing withon Biden and his son . The memo says the campaign plans to "focus on the issues that impact people's lives while simultaneously hammering Donald Trump for his unprecedented abuse of power and correcting the record on the mountain of lies Trump and his allies continue to spread about Joe Biden."
The memo highlighted a new $6 million ad campaign across broadcast and digital platforms in four early contest states. The ad is called "Unhinged" and focuses on Biden's response to Mr. Trump's comments.
Speaking to reporters on Friday, Biden said to "focus on this man and what he is doing" when asked if there was a conflict of interest inof a Ukrainian energy company while he was vice president.
Mr. Trump fired off a series of tweets targeting Biden on Sunday afternoon, saying he "would LOVE running against 1% Joe Biden - I just don't think it's going to happen."
Andrew Bates, a Biden spokesman, called the tweets "puzzling ... seeing as how he just sent his administration into a tailspin by trying to bully a foreign country into spreading a comprehensively-debunked conspiracy theory about the vice president."
"Soon Trump will run out of countries he can pressure to bail him out politically, and he will lose the old-fashioned way: an intervention by his own country — courtesy of the American people — in 2020," Bates said in a statement to CBS News.
In an exclusive interview on Friday, CBS News asked Jill Biden whether she saw "any conflict of interest by having had Hunter on the board of a foreign company" while her husband was vice president.
"No, I don't," Jill Biden said. "I know my son Hunter. I know his values. I know his heart. I know that Donald Trump is scared to death of Joe Biden."
Biden gave his most forceful rebuke to Mr. Trump so faron Wednesday, painting Mr. Trump as "wounded" and "desperate."
"Let me make something clear to Trump and his hatchet men and the special interests funding his attacks against me — I'm not going anywhere," Biden said, to applause from the crowd. "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."
Mr. Trump has insisted he wants to investigate alleged corruption by the Bidens. "I don't care about Biden's campaign, but I do care about corruption," Mr. Trump said on Friday.
The president has not offered any proof of his accusation that Biden asked a Ukrainian prosecutor to drop a probe involving Hunter Biden. And on Friday, Mr. Trump called on China to investigate the Bidens' alleged corruption.
According to the summary of a July call between Mr. Trump and Ukrainian President Volodymyr Zelensky, Mr. Trump urged Zelensky to work with Rudy Giuliani and Attorney General William Barr to look into Biden. The White House had also, at the time of the call, withheld military aid to Ukraine, which has been fending off incursions by Russia-backed separatists.
House Speaker Nancy Pelosi has since ordered an impeachment inquiry stemming from the president's communications with Zelensky and his withholding of the military aid from Ukraine.
Mr. Trump on Saturday, who called Mr. Trump's action on Biden "wrong" and "appalling."
Bo Erickson and Zak Hudak contributed reporting.