Why a top US-senator considers President Trump "utterly untruthful"
What's the story
Senior Republican Senator Bob Corker has attacked US President Donald Trump, calling him "utterly untruthful."
Corker has accused Trump of being a liar and said the president is debasing America and weakening its international standing.
An angry Trump responded by tweeting that Corker is a "lightweight" who "couldn't get re-elected."
The exchange reignites an ongoing feud between the two men.
Accusations
Corker believes Trump is ruining US' relations with other countries
"He is purposely breaking down relationships we have around the world that had been useful to our nation," Corker told CNN.
"I think the debasement of our nation is what he'll be remembered most for," he added.
Corker, the chairman of the powerful Senate Foreign Relations Committee, was an early Trump supporter.
"I would not do that again," he said about supporting Trump.
Trump hits back
Trump accuses Corker of 'setting the US way back'
In a series of tweets, Trump said Corker, who helped President Barack Obama "give us the bad Iran Deal & couldn't get elected dog catcher in Tennessee, is now fighting Tax Cuts."
"People like liddle' Bob Corker have set the U.S. way back," he added.
His tweets came after Corker suggested the president shouldn't interfere in the tax legislation debate.
Information
After trading barbs, Trump and Corker meet to discuss tax
Trump and Corker met after trading barbs to discuss tax reform at a Senate lunch. Corker's support for the Republican tax plan would be crucial to get legislation passed in the Senate. It appears Corker, who is on the verge of retirement, won't back down.
More criticism
Outgoing Republican Senator Jeff Flake accuses Trump of undermining democracy
Meanwhile, Republican Senator Jeff Flake has joined Corker in criticizing Trump.
He slammed Trump over his "flagrant disregard for truth or decency, the reckless provocations, most often for the pettiest and most personal reasons."
"We must never regard as 'normal' the regular and casual undermining of our democratic norms and ideals."
Flake, who was up for re-election, announced his retirement at the Senate.
Protest
Protester throws Russian flags at president, shouts "Trump is treason"
In the middle of all this, police have arrested a protester who hurled Russian flags at Trump while he was walking through Capitol Hill.
The protester, identified as Ryan Clayton, shouted, "Trump is treason."
He cried: "This president conspired with agents of the Russian government to steal an election!"
Clayton is part of Americans Take Action, a group seeking Trump's impeachment.