President-elect Donald Trump dismissed charges Sunday that his victory was illegitimate, lashing out on Twitter at critics who point to Hillary Clinton’s lead of more than two million votes in the national popular vote as evidence.

“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 tweeted, without providing any corroboration for the allegation.

Voting is restricted to U.S. citizens, and no evidence has emerged so far of widespread voting by illegal immigrants.

“It would have been much easier for me to win the so-called popular vote than the Electoral College in that I would only campaign in 3 or 4 states instead of the 15 states that I visited. I would have won even more easily and convincingly,” Mr. Trump said in another tweet.

Separately, officials in three states that gave Mr. Trump his margin of victory this month are gearing up for recounts in the face of heated pushback from Mr. Trump and his advisers.