Trump could face challenge in 2020 primary, Republican warns

US President Donald Trump may face competition to be the Republican party's nominee for the 2020 White House race if he decides to pursue a second term, a US senator said in an interview broadcast Sunday."If he's the Republican nominee again, we're likely to see an independent candidate" in the November 2020 presidential election, said Flake, who announced this fall that was stepping down from his Senate seat in late 2018."He's probably inviting a Republican challenge as well" for the 2020 prima