Joe Biden has declared "each ballot must be counted" as he pushed back against Donald Trump's bid to halt the US election results process.
The Democrat candidate said he feels "very good about where we stand" and has "no doubt" he will be declared the winner.
Speaking from his home town of Wilmington, Delaware, he tried to burnish his credentials as a statesman, saying he had received briefings on the coronavirus crisis and state of the economy.
And in the statement that lasted only a few minutes, Mr Biden also admitted "democracy is sometimes messy", but insisted "the process is working" and urged people to "stay calm".
It comes as five nail-biting races in battleground states remain too close to call.
Mr Biden is just 17 Electoral College votes short of the 270 either candidate needs to clinch the White House.
If he takes Pennsylvania, where Donald Trump is ahead but seeing his lead shrink, that would give Mr Biden 20 more and push him over the line.
Mr Trump has already claimed victory in the election and accused his political opponents of a "fraud on the American public", calling for counts in four states to cease.
He is claiming - without evidence - widespread ballot tampering, with his campaign launching legal action to try to force a pause in the calculation of results.
But they have already lost one lawsuit in Michigan, and a witness they claimed was the victim of voter fraud in Nevada has been dismissed by the local registrar.
Mr Trump is due to make a statement at 6:30pm (11:30pm GMT), having not been seen since election night. He has been firing off lots of statements flagged as potentially misleading by Twitter from the White House.
The president has also vowed to take his fight to the Supreme Court and his son, Eric, has called for him to "go to total war" over the "cheating" - again unsubstantiated - "that has been going on for far too long".
In Nevada, more results are not expected until Friday.
In Pennsylvania, secretary of state Kathy Boockvar said "the overwhelming majority of ballots will be counted by Friday".
She also denied there was any evidence of voter fraud apart from one case of a man trying to get a ballot for a deceased relative that was discovered several weeks ago.
'Biden plays the role of reassurer-in-chief'
Analysis by Cordelia Lynch, US correspondent
Joe Biden is trying again to get on the front foot by delivering a brief statement.
It looked like a very overt attempt to cast himself as presidential - addressing the COVID-19 situation at the top which still plagues this country.
But it was also an attempt to continue his role as reassurer-in-chief, firmly urging calm, insisting every vote will be counted, irrespective of the president's claims about fraud.
It was succinct but pointed statement - a chance for him to reaffirm he has every faith he will be president soon.