President Trump vowed political payback last year when Republican state lawmakers in Indiana defied him on redistricting, refusing to draw new congressional maps to help the party in the midterms.

He delivered on that threat.

On Tuesday, Republican primary voters backed at least five of the seven challengers whom Mr. Trump endorsed over incumbent state senators, according to The Associated Press. One incumbent was re-elected, and one race was too close to call.

Even as the president’s poll numbers sag, the results in Indiana showed his enduring sway over Republican primary voters and his continuing ability to exact political revenge. Here is what we learned on Tuesday:

Trump still dominates the conversation.

Whether voters were glad to hear from him or wished he had stayed out of a statehouse election, Mr. Trump’s involvement loomed over the campaign.

The challengers backed by the president included his photo on their campaign literature and posted social media photos of themselves at the White House. Some of the incumbents took pains to explain points of agreement with Mr. Trump, even as the president attacked them on social media.

“Tonight was a lesson to Republican lawmakers throughout the nation,” said Senator Jim Banks, an Indiana Republican who backed the challengers. “There are consequences for not representing your voters.”

In Columbus, Ind., south of Indianapolis, Brenda Forgey said the president’s endorsement proved persuasive.

“We are Republicans through and through, and if he endorses anyone, we are behind them,” Ms. Forgey said.

But that same endorsement drove James Vogel, another Columbus voter, to support the incumbent.

“He is ruling by chaos,” Mr. Vogel said of the president. “Every day, every week, it is something new.”

Trump succeeded in his first of several attempts to oust Republicans who defy him.

The result was a stunning rebuke for independent-minded Republicans and a warning to officials elsewhere in the country who have crossed Mr. Trump, the undisputed leader of the Republican Party.

“Donald Trump maintains his singular ability to catapult candidates from obscurity to Congress or, in this case, the Indiana Statehouse,” said Pete Seat, an Indiana-based veteran of the George W. Bush White House. “The organizational heft, the messaging acumen and the level of coordination required to pull off this feat cannot be — and should not be — underestimated.”

The results are surely cause for concern for two Republicans who have bucked Mr. Trump in the past and are now facing primary opponents backed by the president: Representative Thomas Massie of Kentucky and Senator Bill Cassidy of Louisiana.

Like the newly deposed Indiana Republicans, Mr. Massie and Mr. Cassidy have long histories with their constituents and are known quantities locally. But Tuesday proved once again that in a Republican primary, Mr. Trump’s desires often outweigh whatever local good will candidates have built up.

Republican voters were split on Trump.

Indiana voters supported Mr. Trump by large margins in the last three presidential elections. Even still, and even as his preferred candidates racked up victories, Republicans voiced mixed reviews of his second term and were divided about the importance of his endorsement.

“He is doing what he is supposed to,” Athena Purtlebaugh said after she voted for the president’s candidate in Taylorsville, Ind. “Yes, he is coarse sometimes and I cringe, but he is doing the right things.”

But in Tipton, Ind., Jeff Crouch said that “he didn’t want to vote for anybody that was endorsed by President Trump.”

Mr. Crouch, a Republican, said he had voted for Mr. Trump previously, but not in 2024. He described his impression of the president’s second term as “somewhere between terrible and really terrible.”

The fight for the Indiana G.O.P. continues.

Indiana Republicans have amassed near-total control of the state over the last 20 years. But the fight over redistricting brought long-simmering fissures into the open.

The divide is not exactly between moderates and conservatives, but more between the party establishment and an ascendant faction that has modeled its style after the president’s.

On the one side, the state’s governor, lieutenant governor and many members of the congressional delegation lined up behind Mr. Trump.

On the other, former Gov. Mitch Daniels, who helped usher in Indiana’s era of Republican dominance, became a leading voice against redistricting. His successor as governor, former Vice President Mike Pence, mostly avoided the redistricting debate, but endorsed one of the incumbents seeking re-election.

Indiana’s two Democratic congressmen could face inhospitable new maps.

With so many Trump-backed challengers ousting incumbents who had voted against redistricting, the path appears clearer for drawing new maps before the 2028 elections.

Because Republicans hold durable majorities in both chambers of the state Legislature, the results from Tuesday’s State Senate primaries made it more likely there would be support for a G.O.P.-friendly redistricting next year.

It remains unclear how aggressive the new class of Indiana Republicans in the State Senate will be. Democrats hold seats based in Indianapolis, the state capital and largest city, and in the suburban Chicago communities of Northwest Indiana.

Kim Bellware, Robert Chiarito, Amy Lynch and Kevin Williams contributed reporting from Indiana.