President-elect Donald Trump made unsubstantiated claims of serious US voter fraud and said "millions of people" had cast their ballots illegally, offering no evidence for the assertions he put forth on Twitter.
Trump's shock path to the White House saw him fall short of his Democratic rival Hillary Clinton in the popular vote -- she carried the election by 2.2 million ballots -- but win the all-important Electoral College count, which decides the US presidency.
The Republican billionaire's latest statements, in which he said he would have won the popular vote were it not for the "millions of people who voted illegally," came as steps are being taken towards recounting votes in the state of Wisconsin, which Trump won.
Trump and his aides have pushed back hard against that recount, with the president-elect letting loose a series of early-morning tweets in which he quoted Clinton about the need to respect the electoral process.
But by the end of the day, Trump was alleging on Twitter that: "In addition to winning the Electoral College in a landslide, I won the popular vote if you deduct the millions of people who voted illegally."
Although Trump had warned before the election that the result might be "rigged," he had offered no such complaint after his unexpected November 8 victory -- until now.
Back in New York late Sunday after spending the Thanksgiving holiday at his Florida Mar-a-Lago resort with his family, Trump again took to Twitter, alleging that voter fraud had occurred in several states.
"Serious voter fraud in Virginia, New Hampshire and California - so why isn't the media reporting on this? Serious bias - big problem!" Trump posted.
Trump and his aides have offered no evidence concerning the claims, nor did Trump explain why he would oppose the nascent Wisconsin recount if illegal voting was such a serious problem.
No election observers have pointed to any such widespread fraud.
While the recount was requested by Green Party candidate Jill Stein, who received a minute fraction of the total vote in Wisconsin, Clinton's campaign has said it would join the process despite having seen no irregularities in the White House contest so far.
Trump's top aide Kellyanne Conway, in the middle of the turbulence, appeared Sunday to at least hint that if the Clinton team pushes too hard on the Wisconsin recount, the president-elect might rethink his vow not to seek Clinton's prosecution for using a private email server when she was secretary of state.
Conway said on ABC that while Trump was being "magnanimous" toward Clinton, "I guess her attitude towards that is to have her counsel go and join this ridiculous recount."
Marc Erik Elias, an election lawyer for the Democratic candidate, said in a post on Medium.com on Saturday that the campaign would also participate in recounts in Michigan and Pennsylvania if they are arranged.
Most election experts see almost no chance the election outcome could be reversed -- Clinton trails in each state by several thousand votes.
Trump won Michigan, Pennsylvania and Wisconsin by a total of just over 100,000 votes, even while compiling many more than the 270 votes needed for victory in the Electoral College.
The dispute continued to roil what has already been a rough transition period, as serious signs of internal discord over cabinet picks again emerged on Sunday.
The discord centers around the position of secretary of state, with some in the Trump camp supporting Mitt Romney, the 2012 Republican presidential nominee, as a more mainstream choice while others favor the more divisive former New York mayor Rudy Giuliani.
In what political analysts considered a highly unusual public airing of those tensions from within the Trump team, Conway last week tweeted that she had received "a deluge" of concern from people warning against Romney.
Asked about that on Sunday, she told NBC that she was not "campaigning" against Romney, but was "just astonished at the breathtaking volume and intensity of blowback" to a possible Romney nomination.
Trump supporters were infuriated in March when the former Massachusetts governor delivered a passionately worded attack on Trump on the part of the Republican Party's establishment, calling him a "fraud," given to "absurd third-grade theatrics."