(CNN) One of the big questions over the last few months has been why Republican officials are so fearful to speak out against the President. Much of that certainly has to do with ideological agreement with Trump. Some of it, no doubt, is Republicans know that speaking out too much against the President is an electoral death wish.

When you agree with Trump, on the other hand, it can pay dividends in a big way.

On Tuesday night, Georgia Secretary of State Brian Kemp became just the latest Republican to benefit from President Donald Trump's endorsement. Kemp trailed Lt. Gov. Casey Cagle by double digits in the first round of the state's gubernatorial primary . Polling indicated that Kemp was climbing before Trump backed him, but Trump's endorsement seemed to accelerate his surge. In the end, Kemp was able to win the runoff by 39 percentage points.

The Kemp win capped off what has been a strong two months for the President when he waded into competitive Republican primaries.

It all started before the California primary on June 5. Republicans desperately wanted a member of their party to finish as the first- or second-place candidate given the state's top-two primary system. Polls indicated though that Republican voters really weren't sure who to vote for because so many Republicans were running. In came the President with an endorsement on May 18 for John Cox. A few weeks later, Cox easily placed second and got on the ballot for November.

The next big triumph for the President came on June 12 in South Carolina. Rep. Mark Sanford was beaten in his primary by Katie Arrington. Trump made a day-of election endorsement for Arrington that probably didn't move too many votes given how late it occurred. Still, Sanford was dogged on the campaign trail by his general hostile attitude towards the President.

Where Trump's endorsement clearly helped was in the South Carolina's governor's race. Trump backed Gov. Henry McMaster in his primary. McMaster finished first in round one, and then Trump's continual backing — including an election eve rally — allowed him to escape with a narrow victory over businessman John Warren in the runoff a few weeks later. Warren, as I previously noted , fit the Trump mold better than McMaster did. Voters though decided to go with the long-time politician Trump endorsed rather than the Trump-like candidate.

Perhaps most interesting is what occurred in Alabama's 2nd District. Rep. Martha Roby had withdrawn her endorsement of Trump in 2016 after the release of the "Access Hollywood" tapes. Trump though decided to back Roby in 2018 nonetheless. That left Democrat-turned-Republican Bobby Bright with little room to call out Roby for her past statements against Trump. She would win the primary runoff on July 17 by 36 points.

The success of these half-dozen Republican candidates in competitive races shouldn't be too surprising. The President has an approval rating north of 80% with Republicans and north of 90% with conservative Republicans (i.e. the base). He is the leader of the party, so what he says should be pretty important.

What is compelling though is the different types of candidates who seem to be getting a helping hand from Trump. There are those who generally match his profile (like Cox), those who beat candidates who were more like Trump (like Donovan) and those who were once clearly against him (like Roby).

It's not all good news for the president, though. Remember these are Republican primaries. Republican candidates still need to win general elections. The last two Republicans who went down in ruby red territory (Roy Moore and Rick Saccone) both had the emphatic backing of the President.

With Trump's approval rating in the low 40s among the general electorate, he's more likely a detriment to Republicans than a help in the upcoming fall elections.