WASHINGTON (Reuters) – U.S. President Donald Trump said on Wednesday he would seek a major investigation of alleged voter fraud in the November election, despite overwhelming consensus among state officials, election experts and politicians that voter fraud is rare in the United States.

“I will be asking for a major investigation into VOTER FRAUD, including those registered to vote in two states, those who are illegal and….even, those registered to vote who are dead (and many for a long time). Depending on results, we will strengthen up voting procedures!” Trump said on Twitter.

Trump, who has bristled at references to losing the popular vote to Democrat Hillary Clinton, did not elaborate beyond the two Twitter posts. The Republican real estate mogul and reality television star has never substantiated his claim of voter fraud.

State officials have said they found no evidence of widespread voter fraud in the Nov. 8 election and there is no history of it in U.S. elections. House of Representatives Speaker Paul Ryan, the most senior Republican in Congress, repeated on Tuesday that he had seen no evidence to support it.

Trump won the state-by-state Electoral College tally that decides the presidency but Clinton had about 2.9 million more popular votes.

The popular vote and allegations of Russia influencing the election on Trump’s behalf have led to criticism that his victory was not legitimate.

Trump’s announcement on Twitter follows a White House news briefing on Tuesday in which his spokesman Sean Spicer confirmed that Trump continued to believe that millions of illegal immigrants voted in the election.

Spicer did not provide any evidence to support those beliefs.

Federal investigations of voter fraud are rare. A five-year probe initiated by the George W. Bush administration turned up no evidence of voter fraud and ended in resignations and more investigations for the Department of Justice, which enforces federal voting rights laws.

Trump’s attorney general nominee, Republican Senator Jeff Sessions, has been criticized for his record on voting rights and race relations. A voter fraud case he prosecuted as a U.S. attorney in Alabama in 1986 helped derail his confirmation as a federal judge in 1986.

In a 2007 report titled “The Truth About Voter Fraud,” by the Brennan Center cited voter fraud incident rates between 0.00004 percent and 0.0009 percent.

A study by the Washington Post found 31 credible cases of impersonation fraud out of more than 1 billion votes cast in elections from 2000 to 2014. Arizona State University studies in 2012 and 2016 found similarly low rate.

(Reporting by Doina Chiacu and Susan Heavey; Editing by Chizu Nomiyama and Bill Trott)

IMAGE: Donald Trump speaks at a campaign rally in Sacramento, California. REUTERS/Lucy Nicholson