As the White House rejected calls for Donald Trump to tone down his inflammatory rhetoric, investigators confirmed the existence of more pipe bombs sent to the targets of Trump's tirades.

Federal officials reportedly believe that former Vice President Joe Biden might also have been targeted, and are searching the mail system for a package containing a pipe bomb that might be addressed to Mr. Biden.  That one was sent to an address that Biden no longer uses and was returned to sender.

They also confirmed that a second device was sent to California Congresswoman Maxine Waters; this one was intercepted at a Los Angeles postal facility near her district office.  Another device addressed to Ms. Waters' Washington, DC office was caught in the US Capitol Post Office.  "I unequivocally condemn any and all acts of violence and terror," Waters later said.

Other bombs were intercepted before they could reach the other targets:  Former US President Barack Obama; former Secretary of State Hillary Clinton and her husband ex-President Bill Clinton; billionaire financier George Soros, who has donated truckloads of money to Democratic causes; former US Attorney General Eric Holder; and John Brennan, the former CIA director.  All of these people had been vilified by Donald Trump in his tweets, in his comments, and at his campaign rallies.

Obama's people referred questions to the Secret Service.  At an appearance after the bomb scare, Hillary Clinton thanked "the men and women of the Secret Service who intercepted the package addressed to us long before it made its way to our home".  She also spoke of the negativity and anger stirred up by Trump:  "It is a troubling time, isn't it?  It is a time of deep divisions, and we have to do everything we can to bring our country together."

Mr. Brennan on Wednesday said that President Donald Trump's vitriol is "un-American" and has "emboldened individuals to take matters into their own hands". 

"His rhetoric, I think, too frequently fuels these feelings and sentiments that now are bleeding over into, potentially, acts of violence," Brennan continued, "A lot of this rhetoric really is counterproductive, it is un-American, it is what a president should not be doing."

The bomb intended for Brennan was sent to him at CNN, where he frequently appears as a guest on news broadcasts.  Trump has repeatedly referred to CNN and other news outlets as "enemies of the people", and egged on members of his crowd to harass and insult journalists.  CNN chief Jeff Zucker has had enough.

"There is a total and complete lack of understanding at the White House about the seriousness of their continued attacks on the media," Zucker said.  "The president, and especially the White House press secretary, should understand their words matter.  Thus far, they have shown no comprehension of that."

On Wednesday night, Trump held one of his campaign rallies far off in the wilderness of rural Wisconsin, in which he tried to gaslight the media by suggesting increasing violence and madness in America was the result of critical reporting of his administration.