More than 70 percent of respondents in an ABC News/Washington Post poll said they doubt Trump’s word on the Russia issue and 55 percent doubt Comey’s word as well.
The poll comes just a day before Comey's scheduled testimony in the US Congress.
The White House had originally claimed Trump fired Comey in May on the recommendation of US Attorney General Jeff Sessions and Deputy US Attorney General Rod Rosenstein, but Trump later said in he always intended to fire Comey.
Russia has repeatedly denied claims of meddling in the US political process and has called such allegations absurd and intended to deflect US public opinion from actual instances of election-related fraud and corruption as well as other pressing domestic concerns. Kremlin spokesman Dmitry Peskov has said Russia did not have official contacts with Trump's team during the presidential campaign.