New York Times columnist Paul Krugman mocked Donald Trump's claims that he lost the popular vote due to people voting illegally, while floating conspiracy theories of his own surrounding the election.

"So [FBI Director James] Comey and [Russian President Vladimir] Putin installed a crazy, vindictive, can't-handle-the-truth person in the White House. Scary," Krugman tweeted on Sunday.

Trump is losing to Hillary Clinton in the popular vote by around 2 million votes, but has 306 electoral votes compared to Clinton's 232, with 270 required to win the presidency.

Trump tweeted on Sunday that he would have won the popular vote had he campaigned in three or four high-populous states. He added that he would have won the popular vote "if you deduct the millions of people who voted illegally."

Top Democrats and Krugman blamed Comey for Clinton's electoral loss, pointing to his decision to reopen an investigation into Clinton's private e-mail server about two weeks before the election. An examination of Anthony Weiner's e-mails for an unrelated probe into allegedly lewd exchanges with an underage girl prompted the reexamination of the Clinton e-mail probe.

Comey announced a few days before the election that he had not found any new evidence, and reiterated his decision not to charge Clinton.

A report in New York Magazine prompted speculation among Democrats over whether voting irregularities, allegedly from Russia, put Trump ahead in states Wisconsin, Michigan and Pennsylvania.

Currently there is no hard evidence to suggest of such irregularities. However, Green Party Nominee Jill Stein requested a recount in Wisconsin and is eyeing a similar request in Michigan and Pennsylvania.

The Clinton campaign said it would participate in the recount process.