In a tweet, Trump suggested delaying the 2020 elections and claimed that increased postal voting could lead to fraud and inaccurate results.
About half of U.S. states allow any registered voters to cast their ballot by post on request, and six U.S. states were planning to hold all-mail ballot elections this November: California, Utah, Hawaii, Colorado, Oregon, and Washington.
Furthermore, we have previously reported that voter fraud is very rare in the United States, and mail-in ballots will not substantially increase the risk of voter fraud. President Trump's advisory commission on election integrity spent eight months, from May 2017 to January 2018, probing claims of voter fraud and did not turn up a single confirmed instance. A Washington Post review of data from after the 2016 election found just four confirmed cases of voter fraud: three people who tried to vote for President Trump twice, and an election worker in Miami who was caught trying to fill in someone else's ballot for a local mayoral candidate. A study titled 'An Analysis of Voter Fraud in the United States' published by Demos in 2003 analyzed the incidence of voter fraud from 1992 to 2002 in 12 states, which collectively represent about half of the electorate. The study found that voter fraud was very rare in those 12 states and legal and news records had little evidence of significant voter fraud. In conclusion, the report indicates that fraud is a minor problem in the U.S.