Republican senator Richard Burr has been censured in North Carolina after voting to convict Donald Trump, making him the latest GOP lawmaker to confront a backlash over breaking with the former president.

Republican officials in North Carolina voted unanimously on Monday to censure Burr over his vote finding Trump guilty in the former president’s second impeachment trial. The state party officials said they believed it was unconstitutional to try a former president.

“It is truly a sad day for North Carolina Republicans,” Burr said after the vote. “My party's leadership has chosen loyalty to one man over the core principles of the Republican party and the founders of our great nation.”

Burr was one of seven Republican senators who voted against the president at the conclusion of his Senate trial at the weekend. Burr’s colleague Bill Cassidy of Louisiana was already censured by his state party, which said it “condemned” his vote finding Trump guilty of inciting the January 6 siege at the US Capitol that left five people dead.

Trump was acquitted because the US constitution stipulates that conviction requires the support of two-thirds of the 100-member Senate. Fifty-seven senators found Trump guilty after a five-day trial, while 43 voted not guilty.

The result — in which more lawmakers voted against a president of their own party than in any impeachment trial in US history — exposed sharp divisions in the Republican party, as lawmakers wrestled over how to move forward with Trump no longer in the White House.

Republican operatives are at war over whether to field rightwing, Trump-supporting candidates in next year’s midterm elections or to endorse more centrist GOP hopefuls in an attempt to win back the moderate Republicans and independents who abandoned the party at the ballot box last November.

Burr is far from the only Republican to face rebuke for voting against Trump.

Adam Kinzinger, one of 10 House Republicans who voted to impeach Trump last month, revealed on Monday that he received a two-page letter from family members calling him a “disappointment” to God for his opposition to the former president.

The letter, first published by the New York Times, added: “You have embarrassed the Kinzinger family name!”

Burr and Cassidy joined Maine’s Susan Collins, Alaska’s Lisa Murkowski, Mitt Romney of Utah, Ben Sasse of Nebraska and Pennsylvania’s Pat Toomey in voting to convict the president at the weekend. Burr’s vote came as a surprise to many in Washington, as he had been less publicly critical of the former president than many of his colleagues.

Burr, who was last elected in 2016, has long said he will not seek re-election in the 2022 midterms, when Republicans will look to take back control of both the House of Representatives and the Senate.

Thom Tillis, the other Republican senator from North Carolina who voted to acquit in Trump’s impeachment trial, released a statement late Monday calling Burr a “great friend and a great senator who has a distinguished record of serving the people of North Carolina”.

“He voted his conscience,” Tillis said.

An ABC News-Ipsos poll published on Monday found 58 per cent of Americans thought Trump should have been convicted in his Senate trial. But while 88 per cent of Democrats and 64 per cent of independents said the former president should have been found guilty, just 14 per cent of Republicans supported convicting him.

Lindsey Graham, the Republican senator from South Carolina and a fierce Trump ally, said at the weekend that Burr’s vote for impeachment paved the way for Lara Trump, the former president’s daughter-in-law, to run for his Senate seat next year. Trump supporters argue the impeachment result has fired up the former president’s base of supporters and will motivate them to turn out in primaries to nominate candidates for the midterms.

“My dear friend Richard Burr . . . just made Lara Trump almost a certain nominee for the senate seat in North Carolina to replace him,” Graham told Fox News on Sunday. “She represents the future of the Republican party.”

North Carolina is one of a handful of swing states where previous elections have been won by narrow margins, and where Republicans and Democrats are both expected to devote resources in hopes of picking up seats in 2022.

Senate races in Pennsylvania, where Toomey is not seeking re-election, and Georgia, where Democrat Raphael Warnock will look to defend the seat he won in a special election last month, are also likely to be hotly contested.

Donald Trump has not ruled out running for president again in 2024, though he is facing multiple criminal probes, including an investigation into the Trump Organization’s finances in Manhattan, and one into his efforts to interfere in the presidential election in Georgia.