President Donald Trump posted a series of racist tweets telling four progressive congresswomen of color to "go back" to their "countries" on Sunday morning.

While most prominent Democratic leaders condemned the tweets as xenophobic and bigoted, far fewer of their Republican colleagues have done the same.

Openly criticizing Trump — who values loyalty above all else — can be akin to a political death sentence in today's Republican party.

Here are the current and former Republican politicians who have risked drawing Trump's ire and openly denounced his tweets.

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In the early hours of Sunday morning, President Donald Trump poured fuel onto the flames of an ongoing feud between Democratic leadership and four progressive congresswomen of color with a series of racist tweets telling them to "go back" to their "countries."

He charged that the congresswomen "originally came from countries whose governments are a complete and total catastrophe, the worst, most corrupt and inept anywhere in the world" and wondered, "why don't they go back and help fix the totally broken and crime infested places from which they came. Then come back and show us how it is done."

In the past few weeks, tensions between House Speaker Nancy Pelosi and the congresswomen, Rep. Alexandria Ocasio-Cortez of New York, Rep. Ilhan Omar of Minnesota, Rep. Rashida Tlaib of Michigan, and Rep. Ayanna Pressley of Massachusetts, have spilled out into the open.

Read more: Republican silence on Trump's racist tweets shows how fearful they've become of defying him and losing voters

Just one of those members, Omar, was born outside the US, coming to America as a refugee from Somalia at a young age. Ocasio-Cortez, whose parents are from the US territory Puerto Rico, was born in New York City. Tlaib, who is Palestinian American, was born in Detroit, and Pressley, who is African American, was born in Cincinnati.

Dozens of Democratic presidential candidates and fellow congressional Democrats came to the defense of the congresswomen and condemned Trump's remarks as open racism and bigotry, but far fewer Republicans have spoken out to denounce them.

In a Tuesday morning tweet, Trump claimed he didn't have a "racist bone" in his body and encouraged Republicans to vote against a House resolution condemning his comments, writing, "the so-called vote to be taken is a Democrat con game. Republicans should not show 'weakness' and fall into their trap."

Openly criticizing Trump — who values loyalty above all else — can be akin to a political death sentence in today's Republican party, but at least 40 current and former GOP members of Congress and governors are starting to speak out.

Here are the prominent Republican politicians who have denounced Trump's tweets: