McMaster was the first statewide elected official to back Trump's 2016 presidential campaign but has faced questions over corruption in state government.
That was evident earlier this week when GOP voters booted out incumbent Congressman Mark Sanford in Tuesday's primary elections. He first claimed he'd been "hiking the Appalachian Trail" but later admitted to an extramarital affair in Argentina.
In Virginia, several Democrats - especially women - won congressional primaries.
"Robert De Niro, a very Low IQ individual, has received to many shots to the head by real boxers in movies", Trump tweeted - presumably a delayed response to DeNiro's Sunday night speech at the Tony Awards.
Sanford is the second incumbent House Republican to lose a primary this year - and the latest victim of intense divisions among the GOP in the Trump era.
In South Carolina, Trump also had weighed in for Gov. Henry McMaster, an early supporter of the president's 2016 campaign.
In Nevada's U.S. Senate primary, Jacy Rosen easily won the Democratic primary with 78 percent of the vote and Dean Heller easily took the Republican primary with 70 percent, according to The New York Times. After the shooting at congressional Republicans' baseball practice, Sanford on MSNBC said Trump is "partially to blame for demons that have been unleashed" in American politics.
Sanford weathered an extramarital affair in 2009 while he was governor of SC, and was elected to his current position in 2013.
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Square Enix revealed details about the game via a trailer released in April 2018 that can be seen at the top of the page. It was announced days ago that the game would arrive in January 2019 for the Xbox One and PlayStation 4 .
Argentina forward Lionel Messi gives Harbhajan Singh sleepless nights
The enduring memory of that night is Messi taking leave of his seat in the stadium by the time Spain had scored their sixth. It is possible that they could hang on until '22, though Messi has indicated this could be his worldwide swan song.
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In his address President Trump spoke about his recent appearance at the G7 summit , "I had a very good meeting with the G7". Market! Trump initially refused to sign the statement, but agreed to sign it prior to his departure.
Outgoing Rep. Mark SanfordMarshall (Mark) Clement SanfordMark Sanford: I pledge allegiance to the flag, not to Trump Ana Navarro: Republicans are "cowards" for not standing up to Trump The Hill's Morning Report - Can the economy help Republicans buck political history in 2018?
President Trump threw his support behind the primary opponent of a sitting Republican House member Tuesday afternoon, with just hours to go before the polls closed in SC. Harry Reid. Angle, who lost to Reid in her 2010 bid for Senate, lost her primary challenge to Rep. Mark Amodei on Tuesday.
In a big Virginia race, Republican Corey Stewart - known for his ardent defense of Confederate symbolism - won the Republican primary to face Democratic Sen.
"He's MIA and nothing but trouble", Trump continued.
While Sanford had already expressed reservations at his chances of winning, Trump's tweet appeared to be the nail in his coffin.
Both primaries were sleepy, but the two states will be among the nation's most competitive Senate battlegrounds in the fall.
Republicans in Congress said the message came in loud and clear Tuesday night: Oppose President Donald Trump and it could cost you your seat.
McMaster was the top vote-getter in Tuesday's primary but failed to win the 50 percent necessary to avoid a runoff. Afghanistan veteran and longtime state Rep. James Smith is the front-runner, spending 22 years in the South Carolina House before stepping aside for a run for governor.
Voters also cast ballots in Maine, Nevada and North Dakota, as the field for the mid-term elections begins to take shape.