Trump's own attorneys have conceded there is no evidence of voter fraud

President Donald Trump on Tuesday called for a "major investigation" into his unsubstantiated claims of widespread voter fraud - but his own lawyers are on record saying there is no such evidence.

Late last year, attorney's representing Trump had written as much in court filings submitted to squash recount efforts by Green Party nominee Jill Stein in Michigan and Pennsylvania, The Washington Post reported.

In the filing submitted in Michigan on behalf of Trump's campaign, Trump's lawyers made a direct statement that no evidence pointed to voter fraud existing in the 2016 election.

"On what basis does Stein seek to disenfranchise Michigan citizens? None really, save for speculation," the filing read. "All available evidence suggests that the 2016 general election was not tainted by fraud or mistake."

The lawyers wrote the purpose of Stein's recount effort was "to sow doubts regarding the legitimacy of the presidential election."

In Pennsylvania, the filing did not go quite as far as to make such a direct statement, but kept the sentiment focused on the Keystone State.

"On what basis does Stein seek to disenfranchise the voters of the Keystone state?"it read. "None really. There is no evidence - or even any allegation - that any tampering with Pennsylvania's voting systems actually occurred."

Trump had, in late November, falsely claimed that "millions" had voted illegally in the election, enough to have swung the popular vote in favor of Democratic presidential nominee Hillary Clinton by nearly 3 million votes. He also claimed without evidence that "serious voter fraud" occurred in Virginia, New Hampshire, and California - all states that he lost. The secretaries of state for each of the three states mentioned strongly rebuked Trump's assertion and said no such fraud took place.

The false assertion from Trump was brought back into the forefront this week when he brought up the claim during a Monday evening meeting with congressional leaders, much to the dismay of several Republicans. The assertion has been unsupported by evidence, and Trump has produced none of his own showing as much. It's been repeatedly shot down by fact-checkers and voting officials.

White House press secretary Sean Spicer was repeatedly grilled by reporters about the claims on Tuesday, saying that the voter fraud claim is "a longstanding belief [Trump] has maintained." He would add that the "belief" was based off of "studies and evidence" he's been presented. Spicer said the president believed that as many as 3 million to 5 million people voted illegally in November's election.

The study cited by Spicer, and one previously cited by Trump during the campaign, did not prove his assertions. Authors of both have said they did not prove Trump's assertions at all.

When asked if this belief would spark an investigation, Spicer said "maybe we will." He did not answer whether he personally believed that millions voted illegally.

Trump followed up on Wednesday morning by announcing his intention to start an investigation.

"I will be asking for a major investigation into VOTER FRAUD, including those registered to vote in two states, those who are illegal and," he tweeted, following up in a subsequent message with, "even, those registered to vote who are dead (and many for a long time). Depending on results, we will strengthen up voting procedures!"