WASHINGTON, May 19 (Xinhua) -- U.S. President Donald Trump on Sunday accused Fox News of "wasting airtime" over its coverage of Democratic presidential contender Pete Buttigieg.

"Hard to believe that @FoxNews is wasting airtime on Mayor Pete, as Chris Wallace likes to call him," he wrote, referring to Buttigieg, the 37-year-old openly gay mayor of South Bend, U.S. state of Indiana, and the Fox News host.

Fox News is scheduled to host a town-hall event with Buttigieg on Sunday night.

"They forgot the people who got them there. Chris Wallace said, 'I actually think, whether you like his opinions or not, that Mayor Pete has a lot of substance ... fascinating biography.' Gee, he never speaks well of me," the president wrote.

Buttigieg, who announced his presidential bid last month, is among two dozen contenders for the Democratic nomination to challenge Trump in 2020.

Wallace, 71, has praised Buttigieg as having "interesting, refreshing ideas" and more "substance" than Beto O'Rourke, another White House hopeful.

The Fox News anchor is the son of legendary "60 Minutes" correspondent Mike Wallace, who died in 2012.