If anyone doubted the weight President Trump's endorsement carries in Republican politics, voters in Georgia provided convincing evidence that he dominates the party's base.

Politico:

Georgia Secretary of State Brian Kemp won the Republican nomination for governor of his state Tuesday night, following a late endorsement by President Donald Trump.

Kemp defeated Lt. Gov. Casey Cagle in the primary runoff, two months after Cagle finished ahead of Kemp in the initial primary.  But neither man got the requisite majority to win the nomination, prompting the head-to-head contest.

Kemp's endorsement via Twitter last week has powered the runner-up in the primary race for governor to a massive landslide victory in the run-off election held yesterday.

Brian Kemp is running for Governor of the great state of Georgia. The Primary is on Tuesday. Brian is tough on crime, strong on the border and illegal immigration. He loves our Military and our Vets and protects our Second Amendment. I give him my full and total endorsement.

— Donald J. Trump (@realDonaldTrump) July 18, 2018

Via New York Times.

There is some history to this endorsement.  Cagle was a supporter of Jeb!, while Kemp was a Trump enthusiast in 2016.  Cagle's endorsement by Georgia governor Nathan Deal was of inadequate heft to counter Trump's hold on GOP voters.

This win sets up a contest in November between the Democrats' black female nominee, Stacey Abrams, and Kemp.

Abrams, the former state House minority leader who would be the nation's first black female governor if elected, has campaigned on spending more on education and other services, and on expanding voting rights – an issue that has already brought her and Kemp into conflict.  Abrams has said her path to victory relies on bringing Georgia residents who don't typically vote to the ballot box this November, and her nonprofit has worked to register large numbers of voters in the past.  But Kemp is a proponent of voter ID laws criticized by Abrams, and in 2014, his office criticized Abrams' voter-registration group for allegedly improperly submitting thousands of new voter forms.

This midterm election is shaping up as a showdown.