Here is the letter Sen. Harry Reid received after Election Day in 2010:
Reid had just won a hard-fought re-election against Sharron Angle. Trump had given $4,800 to Reid's campaign.
On Sunday, Reid's office provided the letter to BuzzFeed News after Trump had tweeted that incoming minority leader Chuck Schumer is "far smarter" than Reid.
The Trump transition team did not immediately return a request for comment.