Republicans have won back control of the House of Representatives, scraping a victory from a midterm election that many had expected to be a red wave of wins but instead turned into more of a trickle.

Nevertheless, the party finally won its crucial 218th seat in the lower chamber of Congress, wresting away control from the Democrats and setting the stage for a showdown with Joe Biden in the next two years of his presidency.

The result means the end of Democrat Nancy Pelosi’s time as House speaker. She is likely to pass the gavel to the Republican leader Kevin McCarthy, who has announced his intention to take up the post.

Control of the House is crucial as it will allow the Republicans to launch an array of congressional investigations into issues ranging from Biden’s botched withdrawal from Afghanistan to more obviously politicised probes of government actions during the Covid pandemic and Biden’s son Hunter’s business activities.

The Republican-run House is likely to be a raucous affair as its predicted slim majority means it will take only a few rebels to stymie any legislation – in effect handing great power to almost every Republican member of the House. With the Republican right full of fringe figures, including Georgia’s Marjorie Taylor Greene, that could be a recipe for chaos and the promotion of extremist beliefs and measures.

Biden congratulated McCarthy on the victory and said he was “ready to work with House Republicans to deliver results for working families”.

“Last week’s elections demonstrated the strength and resilience of American democracy,” the president added. “There was a strong rejection of election deniers, political violence, and intimidation.”

Biden and his party had gone into election day largely expecting to get a thumping from an electorate angry at high inflation that has wrought misery for millions of Americans struggling with bills and spiraling prices. Republicans had doubled down on that by running campaigns that stoked fears of violent crime and portrayed Democrats as far-left politicians out of touch with voters’ concerns.

But the Democrats fought back, pointing out the extremist nature of many Republican politicians, especially a cadre of far-right figures backed by Donald Trump, and warning of the threat to US democracy they represented. They were also boosted by the backlash from the loss of federal abortion rights, taken away by a conservative-dominated supreme court.

The result was a shock: Democrats held up in swathes of the country and while Republicans won in some parts, such as Florida, in many other parts their candidates were defeated. High-profile Trump-backed candidates such as Mehmet Oz and Doug Mastriano in Pennsylvania lost their races.

Meanwhile, Republican performance in the Senate was worse. Democrats retained control of the upper chamber when their incumbent senator was projected as the winner in Nevada the Saturday after election night.

The remaining seat up for grabs, in Georgia, will be decided in a run-off between incumbent Raphael Warnock and his Republican challenger Herschel Walker in early December after neither surpassed 50% of the vote.

If Warnock wins, Democrats will enjoy a one-seat majority, 51-49, in the 100-seat senate, a small but significant improvement on the current 50-50 balance, which leaves Democrats in control because the vice-president, Kamala Harris, has the tie-breaking vote.

That situation will continue if Walker wins the seat for the Republicans.