Campaign 2012 was a vintage year for House members seeking promotion to the Senate: A dozen tried, and half of them made it.

There were an imponderable number of other variables, of course, but that 50 percent success rate would suggest that the oldest up-or-out move in the American political playbook is working better than ever. In the five previous elections, 16 of the 45 House members who staked their careers on a run for Senate succeeded in moving to the north side of the Capitol — still, a winning bet 36 percent of the time.

So why are so many current House incumbents saying, “No, thanks,” to opportunities to run for the “upper chamber”?

Maybe we need to look elsewhere for explanations about the rush of demurrals in the past few days by congressmen who looked like locks to run for Senate seats opening up next year: Republican Steve King of Iowa and a pair from Georgia, Republican Tom Price and Democrat John Barrow, who all said they’d seek re-election to the House instead.

Before that came word that Tom Latham had rebuffed a full-court press by GOP recruiters hoping to change his mind about the Iowa race, and the announcement from John Kline, dean of the Minnesota delegation, that he wanted to stay chairman of the Education and Workforce Committee for his final two years and so was rebuffing entreaties that he oppose Democrat Al Franken’s bid for a second term. (A longer-shot potential challenger from the House delegation, Erik Paulsen, surprised few on Monday announcing that he wouldn’t run against Franken, either.)

Perhaps most notable of all was the other political announcement Monday, by Stephanie Herseth Sandlin, who said she would not seek to return to Washington after the next election as the new senator from South Dakota. Ousted from the state’s sole House district in 2010, but with her reputation as a leading centrist Democrat intact, she appeared to be the party’s most formidable prospect for holding retiring Tim Johnson’s seat — especially since the incumbent’s son Brendan, the state’s top federal prosecutor, has given every indication that he’s not running after all.

The state of play for House members seeking Senate seats in 2014 is this: Eight are in the hunt for sure, and four of them look like very good bets to the be the nominees of their party: Democrats Bruce Braley in Iowa and Gary Peters for the open seat in Michigan, Republican Shelley Moore Capito for the open seat in West Virginia and Republican Bill Cassidy to challenge Mary L. Landrieu’s quest for a fourth term in Louisiana.

Three others are in the free-for-all for the GOP nomination in Georgia, and neither Jack Kingston, Paul Broun nor Phil Gingrey can claim to be the front-runner. The last is Colleen Hanabusa, who thinks she can oust senatorial appointee Brian Schatz in the Hawaii Democratic primary.

The waiting game now turns to a trio of House members who — like the three who bowed out in the past week — have seemed to be leaning clearly toward running but haven’t made anything official yet. A back-away by Democrat Frank Pallone Jr. in New Jersey or Republican Renee Ellmers in North Carolina would be a surprise. Same for Republican Mike Rogers in Michigan, unless his alternative is to become the nominee to direct the FBI.

Beyond that, there’s a chance that GOP freshman Steve Daines will take a flier at the newly open seat in Montana. And any or all of the House members from Nebraska — Republicans Jeff Fortenberry, Adrian Smith and Lee Terry — would think about running for the open seat there if Gov. Dave Heineman bows out of an expected Senate candidacy for the second election in a row.

With the exception of Barrow, every House member mentioned above holds a politically safe seat. And with the exception of Braley, who looks for the moment like Tom Harkin’s default successor-in-waiting, none of the House members running or thinking about running can fairly be labeled early-line Senate front-runners. Almost all of them, in other words, would be giving up a comfortable political status quo without anything close to a sure payoff.

The question remains, then, what enlightened self-interest would the rest of them have in trying to move to the other side of the Rotunda? The most obvious benefit is that they would be leaving behind the incessant two-year House incumbent protection lifestyle — the necessarily repetitive drumbeat of fundraisers and telephone town halls and weekend flights to the district — for the significantly more stately political pace of the Senate. At least for the first three or four years “out of cycle,” a senator can indulge some guilt-free interest in nighttimes away from the grip-and-grin circuit, weekends spent in personal pursuit and maybe the occasional fact-finding trip abroad.

But, in the modern Senate, that’s about the best upgrade in sight. For those who have no interest in the fine print of foreign treaties or the inside baseball of confirmation fights, the routine legislative work is about the same as in the House. So are the hours. The pay’s no different at all. And the scheduling vagaries are much more annoying, requiring a numbed embrace of the hurry-up-and-wait school of time management.

The path to becoming a nationally recognized spokesman for your party and a genuine expert in shaping policy on multiple fronts is, of course, more readily available to senators than to House members. But so too is the slide toward frequent ridicule on the late-night talk shows and legislative frustration in the most powerful democratic institution in the world where the majority doesn’t rule.

The constant worry that your most brilliant ideas can be dashed on the dilatory whims of just one even-more-egocentric Senate colleague is arguably worse than the constant awareness that there are far too few microphones for everyone who wants one in the House.

And, beyond all that, the historic prestige differential looks to be closing fast. Hardly anyone refers to the Senate as the upper chamber any more. In an era when a secondary actress on a low-rated TV series is a more sought after guest than a senator at the White House Correspondents’ Dinner, it’s little wonder that Barrow, King, Price and the rest might just as soon be back home on a Saturday night.