When it comes to vote by mail, Trump is once again talking out of his ass.
Colorado has had two vote by mail midterms (2014/2018), a Presidential (2016), and now a vote by mail Presidential primary.
We've been called the safest state in the country to cast a ballot.

Also worth noting: this is not partisan. Vote by mail probably helped elect Cory Gardner in 2014, because older voters liked the convenience and voted early. Younger voters were like "what's a stamp?"
The largest voting demographic in Colorado? Unaffiliated.

Good thread by Rep Matt Gray from Broomfield here: https://twitter.com/matthewogray/status/1246575331663687681