WASHINGTON — President-elect Donald J. Trump said on Sunday that he had fallen short in the popular vote in the general election only because millions of people had voted illegally, leveling his claim — despite the absence of any such evidence — as part of a daylong storm of Twitter posts voicing anger about a three-state recount push.
“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,” Mr. Trump wrote Sunday afternoon.
The series of posts came one day after Hillary Clinton’s campaign said it would participate in a recount effort being undertaken in Wisconsin, and potentially in similar pushes in Michigan and Pennsylvania, by Jill Stein, who was the Green Party candidate. Mr. Trump’s statements revived claims he made during the campaign, as polls suggested he was losing to Mrs. Clinton, about a rigged and corrupt system.
The Twitter outburst also came as Mr. Trump is laboring to fill crucial positions in his cabinet, with his advisers enmeshed in a rift over whom he should select as secretary of state. On Sunday morning, Kellyanne Conway, a top adviser, extended a public campaign to undermine one contender, Mitt Romney — a remarkable display by a member of a president-elect’s team. She accused Mr. Romney of having gone “out of his way to hurt” Mr. Trump during the Republican primary contests.
Officially, Mr. Trump’s transition team has dismissed the recount effort as “ridiculous” and a “scam,” saying there was no evidence of voter fraud that would justify the recounts. Mrs. Clinton’s campaign has also said that it has turned up no signs of such fraud or other irregularities, and the Obama administration has issued statements expressing its confidence in the validity of the vote tallies.
But Mr. Trump appeared fixated on Sunday on the recount and his electoral performance. In a series of midafternoon Twitter posts, not long before he boarded a flight to New York from Florida, Mr. Trump boasted that he could have easily won the “so-called popular vote” if he had campaigned only in “3 or 4” states, presumably populous ones.
“I would have won even more easily and convincingly (but smaller states are forgotten)!” he wrote.
The afternoon messages followed a string of early-morning Twitter posts in which the president-elect railed against the recount efforts. In an initial post at 7:19, Mr. Trump wrote: “Hillary Clinton conceded the election when she called me just prior to the victory speech and after the results were in. Nothing will change.”
He went on to quote a comment by Mrs. Clinton during one of their debates, in which she said she was horrified by Mr. Trump’s refusal to say that he would accept the outcome of the election. And he noted that in her concession speech, she had urged people to respect the vote results.
“‘We have to accept the results and look to the future, Donald Trump is going to be our President,’” Mr. Trump wrote on Twitter, quoting Mrs. Clinton. “‘We owe him an open mind and the chance to lead.’ So much time and money will be spent — same result! Sad.”
One person who spoke with Mr. Trump over the holiday weekend said the president-elect had appeared to be preoccupied by suggestions that a recount might be started, even as his aides played down any concerns. Another friend said Mr. Trump felt crossed by Mrs. Clinton, who he believed had conceded the race and accepted the results.
Mr. Trump’s aides echoed his concerns about the recount effort in appearances on Sunday morning television news programs. Ms. Conway, who was his campaign manager, said on NBC’s “Meet the Press” that Mrs. Clinton and her campaign advisers would have to decide “whether they’re going to be a bunch of crybabies.”
The Clinton campaign will not contribute financially to the recount effort, but it will have its lawyers present at the recount, campaign officials said.