The Republican National Committee is going all-out to try to discredit former FBI Director James Comey, whose new book, A Higher Loyalty, is already making waves. An ABC News/Washington Post poll released Friday finds President Trump and his allies have their work cut out for them. By a 48 percent to 32 percent margin, Americans say Comey is more believable than Trump, and by a similar 47-33 percent margin, they disapprove of Trump's decision to fire Comey — even though Americans don't view Comey all that favorably (30 percent see him favorably, 32 percent unfavorably).

JUST IN: American public finds former FBI Dir. James Comey more believable than Pres. Trump, 48-32%, @ABC News/WaPo poll finds. https://t.co/bzvr6ryhIi pic.twitter.com/r8QOwz6lhX — ABC News (@ABC) April 13, 2018

Americans are much less ambivalent about Special Counsel Robert Mueller's investigation into Russian election meddling and possible Trump campaign collusion. A hefty 69 percent of Americans support the Russia collusion part of the investigation, but 64 percent also back Mueller looking into Trump's business activities — Trump's unilateral "red line" — and 58 percent favor him investigating Trump's alleged hush money payments. Women were 5, 8, and 15 points more likely than men to support those aspects of the investigation, respectively.

ABC News' George Stephanopoulos interviewed Comey, and he offered a preview on Friday's Good Morning America. The excerpt underscored the stakes of the believability question for Trump. "I honestly never thought these words would come out of my mouth," Comey told Stephanopoulos, "but I don't know whether the current president of the United States was with prostitutes peeing on each other in Moscow in 2013. It's possible, but I don't know."

First look at my interview with Former FBI Director @Comey – what he was thinking during those meetings with President @realDonaldTrump https://t.co/TCPSpTzzzr — GeorgeStephanopoulos (@GStephanopoulos) April 13, 2018

The poll was conducted by Langer Research Associates between April 8-11 among a random sampling of 1,002 adults, and the results have a margin of sampling error of 3.5 percentage points. You can find more results at ABC News. Peter Weber