A special election for Alaska’s only seat in the US House was won by the Democrat Mary Peltola, delivering a blow to the former vice-presidential nominee Sarah Palin’s hopes of a political comeback and putting wind in the sails of the Democratic party as it heads for November’s midterm elections.

Peltola’s victory, by 51.5% to 48.5%, marks a stunning turnaround in a state known for its solid conservative leanings. The single House seat was held for almost 50 years by the Republican Don Young, until his death in March.

Donald Trump, who endorsed Palin and campaigned for her at a rally in Anchorage, won Alaska by 10 points in the 2020 presidential election. That marks a swing of 13 points to Peltola’s three-point lead.

Analysts pored over the results of the vote, which was held two weeks ago under a new ranked-choice system but finalized on Wednesday. It was being seen as a significant outcome on several levels – as a potential response to the recent US supreme court overturning of the constitutional right to abortion, to Trump’s enduring grip on the Republican party, and to Palin herself.

The Washington Post pointed out that Democrats have shown gains over their 2020 margins in all five special elections held since abortion right enshrined in Roe v Wade in 1973 was slung out by the Trump-supercharged supreme court in June. Of the five contests, the Alaska result showed the biggest surge in Democratic support.

Democratic strategists will seek to capitalize on this tendency going into the midterms. Prominent Republicans had hoped ending abortion rights would work in their favour but the exact opposite appears to be happening – a progressive wave, given overwhelming national support for the right to terminate a pregnancy in at least some circumstances.

Palin, who left the Alaska governor’s mansion in 2009, had been hoping to use the special election as a stepping stone towards a return to the national political stage. The flamboyant conservative, who styled herself as a “mama grizzly” and who has been seen as a precursor of Trump’s populism, was thrown into the limelight as John McCain’s vice-presidential running mate against Barack Obama and Joe Biden in 2008.

She leant on her celebrity status during the special election, but there were signs of Alaskan voters becoming weary of the cacophony that often surrounds her. Palin is running again for the House seat, which comes up for a regular election in November. It remains to see whether her special election defeat will lead to political support bleeding away.

“Alaskans know I’m the last one who’ll ever retreat,” Palin said in a statement on Wednesday. “I’m going to reload.”

Some Alaskans may, however, remember Palin’s resignation as governor in 2009, when as the Guardian reported, she gave “an at times rambling speech in which she … said only dead fish go with the flow”, prompting critics to “accuse her of a ‘flaky’ decision and walking away from her post”.

After her victory was announced on Wednesday, Peltola, 49, who is Yup’ik and will be the first Alaska Native and woman to represent the state in the House, positioned the result as a reflection of voters’ desire to get back to normalcy after the rancour of the Trump years.

“I think it reveals that Alaskans are very tired of the bickering and the personal attacks,” she told the Post.

Parsing the results is difficult given the state’s adoption of ranked-choice voting. In the first round, Peltola won 40% of the votes while Palin took 31% and her Republican rival, Nick Begich, gained 29%.

The first round indicated clear majority support for Republican candidates – 60% combined – in line with Alaska’s conservative bent. But under the new system, Begich was eliminated and his voters’ second choices were redistributed to Peltola and Palin.

The preferences of Begich’s supporters was striking. Only about half opted as their second choice to back Palin. Almost a third voted for the Democrat and almost as many gave no second choice.

That indicator is likely to increase jitters among Republican leaders concerned about the influence Trump is having on the upcoming midterm elections, which will determine which party controls Congress for the next two years.

There is already intense pressure on several Trump-backed candidates running for the Senate – especially Blake Masters in Arizona, JD Vance in Ohio and the TV doctor Mehmet Oz in Pennsylvania.