President Trump on Wednesday called for a “major” probe into rampant voter fraud — a debunked claim that he insists cost him the popular vote in the election.

“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 in two tweets.

Two days earlier, he griped to lawmakers that 3 million to 5 million illegal votes were cast for Hillary Clinton in the presidential contest.

Neither Trump nor his spokesmen have provided any evidence to back up that claim.

White House press secretary Sean Spicer told reporters Wednesday the investigation would focus on elections in prior years, too, and would focus in part on faulty or fraudulent voter-registration rolls.

“I think in terms of registration, where you’ve got folks on rolls that have been deceased or moved or registered in two counties,” Spicer said. “This isn’t just about the 2016 election. This is about the integrity of our voting system.”

Spicer did not address people who are close to Trump but are themselves registered in multiple states.

They include White House chief strategist Steve Bannon, who until this week was registered in both New York and Florida.

NBC reported he was removed from the registration roll in Sarasota County, Fla., on Wednesday,

The president’s own daughter Tiffany is registered to vote in Pennsylvania and New York, according to Heat Street, and Trump’s treasury-secretary pick, Steve Mnuchin, is registered in New York and California, according to CNN.

Elections officials in New York told The Post it is not illegal to be registered in two states — only to vote in them.

To prove Trump wrong, three Democratic members of Congress sent letters to officials in all 50 states and Washington, DC, asking for any cases of known voter fraud. The letter was signed by Reps. Elijah Cummings of Maryland, Jim Clyburn of South Carolina and Bob Brady of Pennsylvania.