WASHINGTON -- Senator Tom Harkin, the Democrat from Iowa who championed landmark legislation banning discrimination against people with disabilities, said Saturday that he would retire and not seek re-election next year to a sixth term.
The announcement from Mr. Harkin sets the stage for one of the most competitive Senate races in the country in the 2014 midterm elections. It will be a crucial contest in the Republican Party's quest to win control of the chamber from Democrats.
"It's not easy to walk away, but life is fleeting," Mr. Harkin, 73, said in an interview Saturday. "I've had the privilege to be here for 40 years. Too many people hang on to power for too long, and that's not right."
In a Washington career that began in 1974 with his election to the House, which was followed a decade later by his elevation to the Senate, Mr. Harkin has been a forceful voice of populism. He said his biggest achievement was the passage of the Americans with Disabilities Act in 1990, a bipartisan measure he pushed for on behalf of his brother Frank, who was deaf. He was also a leading proponent of overhauling the nation's health care system.
Mr. Harkin sought the Democratic presidential nomination in 1992. But he has played a larger role in subsequent races for the White House as a fierce supporter of the Iowa caucuses that traditionally open the presidential campaign. Barack Obama, as a freshman senator from Illinois, made his Iowa debut at the state's marquee political event in 2006, the Harkin Steak Fry.
The announcement from Mr. Harkin took some Democrats by surprise on Saturday, particularly because he had not signaled his intentions and had a campaign account of nearly $3 million. His is the latest in a series of Senate retirements, and it forces Democrats to try to defend an open seat that would have otherwise been more challenging for Republicans.
"I appreciate that Senator Harkin has made this decision so early in the cycle, giving us ample time to recruit a strong Democratic candidate for this seat," said Senator Michael Bennet of Colorado, the chairman of the Democratic Senatorial Campaign Committee. "Iowa has a strong record of electing great Democrats, and I'm confident that we will elect a new Democratic senator."
Representative Bruce Braley is among the party's early prospects for Mr. Harkin's seat. Mr. Braley had been considering running for governor, but aides said Mr. Harkin's retirement made it certain that Mr. Braley would try to follow the example of Mr. Harkin and jump from the House to the Senate.
Republicans, who need to pick up six seats to win control of the Senate, will probably draw a wide field of candidates. Party officials said one early contender could be Representative Steve King, who has drawn criticism from other Republicans for his outspoken opposition to changing the nation's immigration system.
The race in Iowa, one of the nation's consummate swing states, is still a challenge for Republicans and will be a critical test for the party as it tries to rebuild and recruit candidates who have a wider appeal to voters. Overhauling immigration laws is a top priority of many Republican leaders, and a candidacy by Mr. King could complicate those efforts.
Rob Collins, the executive director of the National Republican Senatorial Committee, said Saturday that Mr. Harkin's planned retirement "immediately vaults Iowa into the top tier of competitive Senate races next year."
In addition to Mr. Harkin, Senator John D. Rockefeller IV, Democrat of West Virginia, has said he will not seek re-election for a sixth term, and there may be other Democratic senators who retire. The party also is contending with a race in Massachusetts, where the successor to Senator John Kerry, who was nominated to serve as secretary of state, will stand for election in November 2014.
Republicans face retirements of their own, including Senator Saxby Chambliss of Georgia, who announced on Friday that he would not seek re-election next year. He was facing criticism from conservatives and could have faced a Republican primary challenge.
This article originally appeared in The New York Times.