(CNN) As President Donald Trump jetted back from a historic summit with North Korean leader Kim Jong Un in Singapore, he got some more very good news in Tuesday's primaries: A prominent Trump critic lost in a GOP primary in South Carolina and a one-time Trump acolyte secured the Senate nomination in Virginia.

The clear message in both races was this: Support Trump and you have a better-than-average chance of winning in a Republican primary. Oppose him -- even occasionally -- and run the risk of losing for your apostasy.

"We are the party of President Donald J. Trump," South Carolina state legislator Katie Arrington declared proudly after defeating Rep. Mark Sanford in the 1st District Republican primary.

Sanford may wind up as the poster boy for what crossing Trump gets you: The South Carolina Republican, who had never lost a race in a political career that spanned more than two decades, lost to Arrington in a campaign entirely cast as a referendum on Trump support.

"[Sanford] talks about working with President Trump on the border wall," Arrington said in one campaign ad. "He was one of only five Republicans who refused to support our President and voted against Trump's border wall. We've all seen Mark on TV attacking our President. Who does he think he's fooling?"

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