In brief
- Republican candidates backed by US President Donald Trump performed strongly in a range of primary contests across six states.
- Midterm elections are typically a referendum on the president in the White House.
US President Donald Trump has flexed his political muscle in the latest Republican primaries, reinforcing his iron grip on the party even as his approval ratings slide.
But with anti-Trump sentiment expected to shape the November midterm elections, his dominance could prove to be either an asset — or a liability.
"We've seen all of Trump's major enemies in the Republican Party being eliminated," David Smith, an associate professor of American politics and foreign policy at the University of Sydney, told SBS News.
In US primary contests, party voters choose candidates to run in a general election.
This week, Republican incumbent Thomas Massie was beaten by Trump-backed candidate Ed Gallrein in the primary race for his Kentucky House of Representatives seat.
The congressman, in office for more than 13 years, had been a thorn in Trump's side for months, calling for the release of the Jeffrey Epstein files and criticising the war in Iran.
Massie, who said before the poll, "I'm going to win", was among the highest-profile casualties as Trump-backed candidates scored a string of victories in primary races across six states on Wednesday AEST.
Trump's political machine launched a well-funded effort to unseat Massie nearly a year ago, after Massie voted against Trump's so-called "big beautiful bill".
The House primary race was the most expensive in years. The race saw more than US$32.6 million ($45.8 million) on ad spending, according to US political ad tracking firm AdImpact. The spending was dominated by Trump-aligned and pro-Israel groups, which targeted Massie with negative ads.
"It really shows us that Trump has a lot of political power over the Republican base even though his popularity with the American public, more broadly, is declining," Smith said.
Why Trump's strength could cut both ways
Midterm elections are often a referendum on the president in office.
Trump's decision to wage war against Iran, a costly conflict that has driven up oil prices and inflation, has been unpopular with US voters. The economy, and displeasure with Trump's leadership, are expected to be defining features of the midterm vote.
Republicans currently control the White House and both chambers of Congress. With the party holding only a slim majority in the House of Representatives, the stakes are high.
"Republicans in swing districts are very, very worried about the Trump effect," Smith said.
Candidates endorsed by Trump often do well in Republican primaries, where conservative voters dominate. But the dynamics shift in general elections, where independents and moderate voters play a larger role.
A recent Politico poll found Trump's endorsement could do more harm than good for Republicans in swing districts, by motivating more anti-Trump voters to turn out.
Republicans in those areas may seek to run more independent-styled campaigns, Smith said.
However, in districts like Massie's — in deep red Kentucky — Republicans are likely less concerned about losing to Democrats.
"The only real contest there is the primaries," Smith said. "But in some other places, Republicans could really be hurt by Trump, and the really big losses the Republicans are having in the polls are coming from independents."
Polling indicates Democrats could reclaim the House of Representatives in November, though an accelerating partisan redistricting battle could complicate the race.
Cory Alpert is a former Biden White House staffer and campaign organiser who has worked on numerous political races for Democrats, including several presidential campaigns.
"I think if it turns out the Democrats end up winning this election in November, it will more be a reflection of dissatisfaction with the Republican party than excitement about the Democratic party," he told SBS News.
Alpert, who is currently a PhD researcher at the University of Melbourne, said if he was advising Democrats in an upcoming congressional race, he'd prefer to be facing a Trump-backed candidate.
"If only because I think this election will largely be a referendum on Donald Trump's presidency," he said.
However, in state-level races, Alpert said Democrats may prefer facing more traditional Republicans, because Trump-aligned candidates can nationalise local contests, sharply increasing fundraising.
Trump's chokehold on the Republican Party
Trump's popularity has taken a hit since he launched strikes with Israel against Iran, setting off a wider war in the Middle East that has had far-reaching effects across the globe.
His approval rating was 35 per cent in the latest Reuters/Ipsos poll — a plunge from the 47 per cent rating he started his term with.
He has lost support from within his own party, with 21 per cent of Republicans disapproving of his performance compared to just 5 per cent when he took office last year.
Still, nearly 80 per cent of Republican voters said he was doing a good job.
Trump's handling of the Epstein files and the war in Iran have driven away some of his most vocal advocates, including former Fox News host Tucker Carlson and former Congresswoman Marjorie Taylor Greene.
"Even though they are very high profile and have very big voices, nonetheless they don't represent the majority of the Republican base," Smith said.
"For the majority of the Republican base they really continue to trust Trump, and at the moment they believe that Trump is unfairly under attack from from all sides."
What happened during the last midterms?
In 2022, while Joe Biden was president, many analysts predicted a "red wave" for Republicans in the midterms which never materialised.
Biden's approval ratings were low at the time, at around 40 per cent, and economic dissatisfaction was weighing heavily on Democrats.
Republicans won back control of the House, but with a much smaller majority than many expected.
According to analysis by the Washington Post after the vote, Republican House candidates endorsed by Trump underperformed expectations in competitive districts, while Republicans without his backing tended to outperform them.
"Democrats were really motivated by the issue of abortion in that election because that was at the time when the Supreme Court was undoing Roe versus Wade," Smith said.
"What Republicans would be worried about the moment is there's no real equivalent issue to motivate Republican voters at this election, and even though Trump has a lot of support from Republican voters, a lot of those same voters just don't turn out when Trump is not on the ballot."
"That was the problem that Republicans had back in 2022, whereas Democrats seem to be very motivated in the lead-up to this election."
For the latest from SBS News, download our app and subscribe to our newsletter.
