It is still early in the primary season, but yesterday’s result in Ohio was a huge win for former President Donald Trump’s continued control of the Republican Party.

The candidate Trump endorsed in a highly competitive primary, author J.D. Vance, beat anti-Trump candidate Matt Dolan and former-state Treasurer Josh Mandel, despite millions spent on ads against him by the Club for Growth.

Looking at Vance’s late surge to the top, it is clear that Trump’s endorsement was absolutely necessary for Vance’s win.

But was it the only reason Vance won? We might find out as the primary calendar unfolds.

On May 17, Pennsylvania Republicans will choose between Trump-endorsed television star Mehmet Oz and retired Army Ranger David McCormick.

Then, on May 24, Georgia will hold its gubernatorial contest between the Trump-endorsed former Sen. David Perdue and incumbent Gov. Brian Kemp. This race is almost entirely about the 2020 presidential election. Trump hates Kemp because of his refusal to go along with Trump’s claims that he won the 2020 election but that it was stolen.

If Trump’s candidates sweep these three races, there will be no avoiding the conclusion that Trump has a personal lock on the Republican Party.

But if Oz’s celebrity-based campaign falters, and Perdue’s 2020 grievance campaign fails to turn out voters, where does that leave the party?

Vance has clearly changed his opinion of Trump, whom he once openly loathed. But he has been entirely consistent on issues since his book Hillbilly Elegy made him famous. Vance has always been a critic of the Republican establishment, which he believes was not doing enough for working families. His campaign has not focused on the 2020 election result but on the points that helped Trump win in 2016 — immigration, trade, and an "America First" foreign policy.

If Vance wins but Oz and Perdue fail, it will show that Republicans have embraced some of Trump's ideological influence, but that Trump's personal hold on Republicans has limits — and also that an "America First" populism could dominate the GOP long after Trump has run his last campaign.