Republicans know Trump's brand is toxic, so they're trying to keep their distance. Sort of.

Republicans are marching in lockstep with Trump, but are refusing to tie themselves to his re-election bid — for now.

On Thursday morning, Sen. Ron Johnson (R-WI) joined a growing list of about two dozen Republican lawmakers — including Sens. John Cornyn of Texas, Lamar Alexander of Tennessee, and John Thune of South Dakota — who have refused to back Trump’s 2020 bid.

When CNN host Chris Cuomo asked whether he will support Trump’s re-election, Johnson tried to dodge the question.

“Chris, you know it’s way too early,” he said and accused Cuomo of engaging in a “gotcha” question.

Other Republicans have similarly tried to dodge the question, claiming it’s too early to talk about 2020. But apparently none of them have told Trump. Trump launched his re-election campaign shortly after taking office and has used it to hold campaign rallies and rake in campaign cash.

When Cuomo pressed the question several times, Johnson still refused to say he’d back Trump in 2020, even though he was adamant about supporting Trump’s agenda.

“We have been four square behind his agenda,” Johnson said, citing as an example the failed attempt to repeal Obamacare.

“Why wouldn’t you back him for his re-election?” Cuomo asked.

“We’re supporting his agenda,” Johnson replied.

“I think you’re in a box here, senator,” Cuomo said.

Johnson is the Trump sycophant who advanced the absurd “secret society” conspiracy theory in Trump’s defense, and even he won’t stand next to Trump for 2020.

This refusal of Republicans to back Trump should not be construed as a signal that they are ready to stand up to him. As Johnson points out, they have all supported Trump’s agenda, and continue to enable his campaign of obstruction against special counsel Robert Mueller.

But as Johnson also points out, Republicans face midterm elections in 2018, and Trump has been toxic to the GOP in special elections since taking office. Tying themselves too closely to his failing presidency is a dangerous game few are willing to play.

This is not about Republicans finding the courage to resist Trump, it is about GOP cowards trying to save themselves from the blue wave that they know is coming.