WASHINGTON — The retirement of Tom Harkin, a Democrat who has represented Iowa in the Senate for nearly 30 years, should be the kind of rare opportunity that sends the best and brightest of his state's political class scrambling to get on the ballot.
But so far the only viable candidate to raise his hand is Representative Bruce Braley, also a Democrat. On the Republican side, one potential candidate after the other has taken a pass — the popular governor, his lieutenant governor, two congressmen and an ambitious state senator who said that he is not willing to have his life turned upside down.
The dearth of candidates for an open Senate seat reflects what former and current senators and those who once aspired to the office say is a sad truth: rarely has the thought of serving in the Senate seemed so unappealing.
Once considered an apex of national politics second only to the presidency, the "greatest deliberative body in the world" is so riven by partisanship and gummed up by its own arcane rules that potential candidates from Georgia to Kentucky, Iowa to Montana are loudly saying, "Thanks, but no thanks."
Add to that the cost of getting there — which can include fighting off special interests and "super PACs" from your own party, exhausting criticism from the increasingly partisan news media, and prohibitive campaign expenses — and a Senate seat no longer seems so grand.
Such weariness is evident not just in the people who are forgoing a Senate bid but also in the exodus of senators not seeking re-election. So far, 8 of the 33 whose terms expire in 2014 have decided not to run again. They include some who probably could have sailed back into office, like Mr. Harkin and his fellow Democrats Carl Levin of Michigan and Max Baucus of Montana, chairman of the powerful Finance Committee.
"In the old days, you'd have to carry the Senate Finance chair out on a stretcher," said Ed Rollins, a veteran political strategist who has advised Republican politicians for four decades, including one in Iowa, State Senator Brad Zaun, who just decided not to run against Mr. Harkin. "There's just not quite the enthusiasm I've seen in other years."
Senate retirements are at the highest levels on record. Since the 2010 elections, a total of 30 senators have bowed out. And more could come yet.
A similar wave of 29 retirements occurred in the mid-1990s, but there is nothing else on record before that quite as large, according to the Brookings Institution's Vital Statistics on Congress, which has data going back to 1930. Ordinarily, only a handful leave with each election cycle.
At this point in 2011, seemingly vulnerable incumbents like Sherrod Brown, Democrat of Ohio, and Jon Tester, Democrat of Montana, had Republican challengers. In states where seats opened up like Nevada and Virginia, the Democratic and Republican sides of the tickets both quickly filled up.
This year there are numerous states with open seats where only one party has a candidate, and many states without a challenger where there is an incumbent the other party would very much like to pick off.
No Democrat has emerged in Kentucky to challenge Mitch McConnell, the Senate Republican leader, despite repeated avowals from Democrats to defeat him. Democrats also have no strong candidate yet in West Virginia, where John D. Rockefeller IV is retiring.
The recruiting troubles for Republicans are worse, in part because gains in the Senate are theirs to lose.
Twenty Democratic-held seats are up in 2014, compared with 13 held by Republicans. And many of those Democratic seats are in states where President Obama lost in 2012 — including North Carolina, Montana, Arkansas and Alaska.
So far, Republicans have no viable declared candidates in any of those red states yet, though conservatives are urging several strong possible contenders to run, like Representative Tom Cotton in Arkansas. Late Friday, Alaska's governor, Sean Parnell, said he would not run, as did Representative Steve King of Iowa.
Senator Ron Johnson of Wisconsin, a Republican first elected in 2010 who is helping his party recruit this year, said his first piece of advice to prospective candidates was to spend $50,000 on an exhaustive opposition research paper on themselves so they can get a sense of what mud might be slung their way. "It can be a pretty miserable process," he said. "And I've got to try and get people over that hurdle."
The reasons for choosing not to run involve many personal factors. They vary from politician to politician, but all share a common thread: a belief that the Senate is too difficult a place to accomplish much of anything these days.
"I don't know that you'd find any legislative body in America — or the world — that's as dysfunctional," said Jay Dardenne, the Republican lieutenant governor of Louisiana, who decided not to run next year against Senator Mary L. Landrieu, a Democrat considered among the most vulnerable.
Like many politicians with aspirations of higher office, Mr. Dardenne says he will instead run for governor, where he said he has a much better platform from which to affect policy in Louisiana. Representative Tom Latham, who declined to run despite encouragement from Iowa Republicans, said the rush to the Senate exits was a warning sign. "It becomes quite clear that there's a lot of frustration," he said. "Some really good people are willing to go home."
Representative Nick J. Rahall, a West Virginia Democrat who was considering a run to replace Mr. Rockefeller, said he believed he could actually be more effective in the House of Representatives — a body hardly known for its functionality. But at least it's a dysfunction he knows. Today's ultrapartisan Senate is radically different from the one he started working in as an elevator operator as a young man. "I never envisioned it getting to where it is," he said.
Another factor keeping people away is the new array of options in the super PAC era — many of them quite lucrative — available to politicians outside of government.
Norm Coleman, the former Republican senator from Minnesota who lost to Al Franken in 2008 and declined to run again, said he had found fulfilling work in his advocacy group American Action Network, which is playing a major role in increasing conservative support for immigration law overhauls.
Now, he said, "I can have a tremendous impact, in many ways a broader reach."
"On the other hand," he went on, "when you're in the United States Senate I don't think there was a person in the world who wouldn't return your call. People still return my calls now. But maybe not as quickly."