Former US senator Orrin Hatch, who retired in 2019 and is one of the longest-serving senators in US history, died on Saturday at age 88, his foundation announced.

The Orrin G. Hatch Foundation wrote on its website that he "passed away at 5:30 p.m. on Saturday, April 23, 2022 in Salt Lake City, Utah, surrounded by family."

A conservative Republican from the western state of Utah, Hatch was elected to the US Senate in 1977, his first public office and a position he held for 42 years.

Through his long tenure in the Senate, where seniority is prized, he was able to rise to the chairmanship of several powerful committees, including those overseeing trade, health care, taxes, and the judiciary.

From 2015 until his retirement in 2019, he served as the president pro tempore of the Senate, a largely ceremonial role that usually goes to the most senior member of the majority party, but which by law is third in the line of succession to the US presidency.

Democratic Senator Patrick Leahy, the current president pro tempore, remembered Hatch as a convivial debate partner.

Former Republican US senator Orrin Hatch died Saturday in Salt Lake City at the age of 88
Former Republican US senator Orrin Hatch died Saturday in Salt Lake City at the age of 88 AFP / SAUL LOEB

"When Orrin and I led the Judiciary Committee we sometimes had profound and difficult policy differences, but we found ways to break the ice," Leahy said on Twitter.

Hatch worked across the aisle to pass multiple major pieces of legislation, such as a 1984 reform to boost generic drug production and the 1997 creation of a health insurance program for poor children.

However, lead Senate Republican Mitch McConnell noted in a statement that Hatch "entered the Senate as a young principled conservative" and "held to his principles his whole career".

As chairman of the Senate Finance Committee in 2017, he was pivotal in passing former president Donald Trump's tax reform package, the biggest legislative success of his presidency.

"Few men have made their mark on the Senate as he did," said Senator Mitt Romney, who was elected to fill Hatch's seat when he retired, in a statement.

"Our judiciary, our economy, and our national character are more elevated and more secure thanks to his years of leadership."