Republican Sen. Ron Johnson Ronald (Ron) Harold JohnsonIG report faults fired FBI official McCabe for leak to media GOP sen: Hope Trump missile tweet is just taking a 'stronger negotiating position' GOP senators cast doubt on spending clawback MORE (Wis.) said Thursday that “it’s way too early” to discuss supporting President Trump Donald John TrumpHouse Dems add five candidates to ‘Red to Blue’ program White House notifies Russia that no new sanctions are coming: report Senators push HHS to negotiate lower prices on opioid overdose reversal drug MORE in 2020. Sen. Ron Johnson, also appearing on CNN today, chastised an anchor for asking if he would support the current Republican president for re-election, calling it a “gotcha question.”

"It could be a completely different world by 2020. We have a 2018 election first.”

Tennessee senator Bob Corker, one of Trump’s most outspoken critics in the Senate, sounded doubtful that Republicans will even have to choose whether to support Trump in 2020.
Republican Senators Ron Johnson and Bob Corker opt not to commit to endorsing Donald Trump in the 2020 elections.