Senator Jeff Flake is not ruling out a challenge to President Trump in 2020.  The Arizona Republican tells ABC's "This Week" he's not planning on making a run for president at the moment, but, "I don't rule anything out."  Flake says he worries about a diminishing GOP base versus a Bernie Sanders or Elizabeth Warren on the far left of the Democratic Party.  Flake says, "That leaves a huge swath of voters in the middle that may be looking for something else." 

Flake is not running for re-election for Arizona senator.

Photo: AOL