WATCH: Trump inadvertently reveals how his election lies cost Republicans control of the US Senate

Months before the 2020 election, Donald Trump began questioning the legitimacy of the vote, repeatedly claiming that it was impossible for him to lose to Joe Biden.

In October, Trump discussed how it would be psychologically devastating if he were to lose the election, going so far as to say he would be so embarrassed he might have to leave the country in shame.

Yet Trump did lose the election and began ramping up his lies that he won.

When voters in Georgia went to the polls for the state's runoff elections in January, many Republicans reportedly believed Trump's lies enough to conclude that there was no point in voting.

Trump discussed the situation during his "Big Lie" rally in Phoenix on Saturday.

"And what happened is we had two senators running, a couple of months later, and you know what happened to them? The Republicans said, 'We're not going out to vote, because this was rigged, this election was rigged,'" Trump explained, inadvertently revealing how his lies hurt the GOP at the ballot box.

The loss of the two seats resulted in Democratic Party control of the U.S. Senate.

Trump-loving lawyer L. Lin Wood threatened a boycott of the runoffs on November 21st.

Republicans in Georgia agreed that Trump cost them the election.

"Trump is the cause of this, lock, stock and barrel," one GOP strategist fumed.

In March, Georgia Republicans warned Trump's ongoing lies could also depress GOP turnout in 2022.