GOP senator torches Trump: 'Saying someone can't do a job because of their race is the literal definition of racism'

Nebraska Sen. Ben Sasse torched Donald Trump over his suggestion that Indiana-born US District Judge Gonzalo Curiel cannot fairly preside over lawsuits against Trump University because of his Mexican heritage.

In a Monday tweet, Sasse, one of the last remaining Republican anti-Trump holdouts, vehemently criticized the presumptive Republican presidential nominee's comments.

"Public Service Announcement: Saying someone can't do a specific job because of his or her race is the literal definition of racism,'" Sasse tweeted.

For his part, Trump maintained that his suggestion that Curiel's heritage made him unfit to preside over the case was not racist.

In an interview that aired Sunday, Trump repeatedly brushed off CNN anchor Jake Tapper's persistent questions about whether his comments about Curiel were racially or ethnically biased.

"If you are saying he cannot do his job because of his race, is that not the definition of racism?" Tapper said.

"No, I don't think so at all," Trump said.

He added: "This judge is of Mexican heritage. I'm building a wall, I'm building a wall."

Sasse was hardly the only high-profile Republican to condemn Trump.

Over the weekend, several Trump supporters - such as Senate Majority Leader Mitch McConnell, current and former House Speakers Paul Ryan and Newt Gingrich, and Sen. Bob Corker - all condemned Trump's comments about Curiel.

"This is one of the worst mistakes Trump has made," Gingrich said.

Though the majority of his Republican colleagues in the Senate have endorsed Trump, Sasse has remained steadfast in his opposition of Trump.

In a fiery open letter published on his Facebook page last month, the senator called for a third-party challenger to both Trump and Democratic presidential frontrunner Hillary Clinton.

"There are dumpster fires in my town more popular than these two 'leaders,'" Sasse wrote.