With almost 94 percent of precincts reporting, Arrington's vote count was at 50.7 percent, to Sanford's 46.4 percent.
The most competitive choice for Democrats appears to be the battle between Clark County commissioners vying to be Nevada's first Democratic governor in two decades. Roby said two years ago that Trump's 2005 lewd comments about women, captured on an "Access Hollywood" microphone, made him "unacceptable as a candidate for president". Last night avid Trump loyalist Corey Stewart won the GOP's nomination for an open Senate seat in Virginia. Tim Kaine in the fall.
In both parties, a dominant theme was the continued emergence of female candidates.
The Republican congressman Justin Amash, a fellow libertarian leaning Trump critic, also tweeted his support for Sanford, in a message aimed at Trump, writing: "He's one of the most principled, consistent, and conservative members of Congress I've ever known".
Arrington also, in a previous Breitbart News radio interview, pledged to join the House Freedom Caucus - a group that now has no women in it but will when she arrives in Congress next year.
Sanford, a principled conservative, said after his defeat that he didn't regret his actions.
McMaster, an early supporter of the president's 2016 campaign, had Trump's full endorsement, marked by a weekend tweet. The president took note of his last-minute intervention in the race.
"I think the thing is representation", Sara Haines explained. "Congrats to Katie Arrington!" the president wrote. The president made reference to a scandal that engulfed Sanford in 2009.
The primary vote could mark the conclusion of a stunning fall for Sanford, whose scandal-pocked career almost ended in 2009, when he acknowledged having a secret extramarital affair with a woman in Argentina while serving as South Carolina's governor.
"Mark Sanford has been very unhelpful to me in my campaign to MAGA". He is better off in Argentina.
"What mattered was are you for or against the president", Sanford, who lost to state Rep. Katie Arrington in the GOP primary, told Anderson Cooper on CNN.
'She is tough on crime and will continue our fight to lower taxes.
The Senate Foreign Relations Committee chairman has been critical of Trump in the past, calling him an "utterly untruthful president" and saying the White House has become "an adult day care center". Twisting the knife, Trump stated that Sanford "is better off in Argentina". And he's just out there, I say, in 'Mark-Land.' It's an academic ideology that does not translate to the actual meat of what America is. Sanford came away from a closed-door meeting less than impressed by Trump's grasp of the U.S. Constitution.
State Senator Jennifer Wexton won the Democratic nomination in the state's 10th district, which includes parts of Northern Virginia.
"So she won 'cause it's just about gender?"
Four other states held primaries.
Sanford previously represented the coastal district from 1995 to 2001.
While it was not all good news for Democrats in Wisconsin on Tuesday - Ann Groves Lloyd, the Democrat running in the special election in Wisconsin State Assembly District 42, conceded to her Republican opponent - national Democratic operatives argue their showing in state legislative races shows voters are prepared to rebuke the President in November. On his website he vows to "defeat political correctness, protect Virginia's history, crack down on illegal immigration, and stand up to the Washington elites".
Also on Tuesday, voters nominated challengers to two of this year's most vulnerable Senate incumbents.
"That's who the party belongs to". Heidi Heitkamp. She is seeking re-election in a state Trump carried by 36 percentage points in 2016.
If Democrats have any shot of winning control of the Senate, they'll need to successfully defend Sen. Tim Kaine and choosing nominees in several competitive House races, Nevada and North Dakota choosing their Senate candidates and ME for the first time trying - and voting on whether to keep - a new voting system in which voters rank their preferences, rather than only selecting one.