"There are no sources," Trump tweeted.
Trump says Clinton was "duped" into bringing up a woman with a "terrible" past.
Supporters are debating whether Clinton needs to go more positive.
The first polls in the days after the debate have shown movement in favor of Clinton.
The Libertarian nominee struggled in a live TV appearance to name a foreign leader he admires.
Trump said he's not worried about the Clintons bringing up his own past.
Trump boasts of forcing the White House to release Obama's birth certificate.
Reports surfaced that Trump violated the U.S. embargo.
The newspaper has never before taken a position in a presidential race.
Trump has offered both praise and criticism of the German leader.