But the president on Tuesday downplayed the possibility that the sharply personal feud with Corker - whom Trump referred to as "Liddle' Bob" in a tweet earlier in the day - could derail his push to find 50 Republican senators to support still-emerging tax overhaul legislation. Corker is central to the success of tax reform, the central GOP priority going forward, and is a key voice in foreign policy.
It is Trump's comments torpedoing talks with the North that appear to have alarmed Corker the most.
Asked if Corker should resign, Sanders said that decision is not for the White House to make.
Trump and top Republican lawmakers have unveiled a plan to slash taxes for businesses and individuals, the first comprehensive overhaul of the US tax code since 1986.
In a 25-minute telephone interview with the Times, Corker questioned Trump's fitness for office and said that the president's recklessness is endangering the country - an assessment he said was shared by most other Senate Republicans.
Trump's jab escalated a war of words between the two that began in earnest on Sunday when Trump claimed that Corker had begged for his endorsement in 2018, then decided not to run for reelection when he couldn't obtain it - an assertion vigorously denied by Corker's chief of staff.
As Trump looks for his first major legislative victory, Corker's vote will be crucial on issues such as the coming tax overhaul bill.
"This is a delicate balance", said Stephen Moore, a fellow at the conservative Heritage Foundation who helped write Trump's campaign tax plan. But it doesn't get you anywhere. Senate Republican Rand Paul has expressed unhappiness over reports that Trump's tax plan could raise taxes on some middle-class Americans.
So who IS Bob Corker?
"Senator Corker worked with Nancy Pelosi and the Obama administration to pave the way for that and rolled out the red carpet for the Iran deal", White House press secretary Sarah Huckabee Sanders said at a briefing.
"While it may really bother other Senate Republicans and it's unnerving that one of their own is being attacked, most aren't retiring and know they must still work with the White House or answer to frustrated voters", Bonjean said.