Pennsylvania’s primary voters have put an exclamation point on one of the lesser-understood realities of modern American politics. Being in the House is just not a good starting point for being elected governor.  

Rep. Allyson Y. Schwartz was soundly defeated Tuesday in her bid to become the Democratic challenger this November against Republican Gov. Tom Corbett, one of the most politically vulnerable state chief executives in the country. Her loss means that, for the 10th time in the past 13 election cycles, half or more of the members who ran for governor were unsuccessful.  

The outcome in Pennsylvania leaves only one other person on the Hill eyeing the top job in a statehouse. That’s Rep. Michael H. Michaud of Maine, who has the Democratic nomination to himself and looks at the moment like a slight favorite come November against Gov. Paul R. LePage, another unpopular GOP incumbent in search of a second term in a currently bluish state.  

The fact that only two members of Congress decided to give up their seats for gubernatorial bids is hardly unusual; the number making that move in the past 25 years has ranged from 11 in 1989-90 to just one last cycle. That was when former House GOP Conference Chairman Mike Pence was elected in Indiana, prompting more buzz about his national prospects in 2016 or beyond.  

But Pence was something of the exception proving the rule. His victory raised the overall record for congressional lawmakers seeking governorships in the past quarter century to 23 wins and 48 losses — a success rate of just 32 percent.  

The result is that, while 49 percent of the Senate’s membership is now made up of former House members, only nine current governors came straight out of Congress. (Two more, independent Lincoln Chafee in Rhode Island and Democrat Mark Dayton in Minnesota, won their positions in comeback bids four years after being pushed out of Senate seats.)  

The facts behind the differing fortunes of this year’s two-member class of gubernatorial aspirants, Schwartz and Michaud, help explain the challenges for House members seeking to move up. From an under-the-Dome perspective, Schwartz appeared to be the more obviously compelling contender. Back when she announced her up-or-out decision 13 months ago, at the start of her fifth term, she had just cemented her standing as a power player in the Democratic Caucus. Having run recruiting for the Democratic Congressional Campaign Committee in 2012, she was put in charge of DCCC fundraising for 2014 and was in the pipeline to contend for the chairmanship of the committee starting in 2015. A longtime health policy expert, she had been returned to the Ways and Means Committee with the expectation she’d be a main voice for her caucus in defending the Affordable Care Act.  

None of that translated persuasively as she sought to position herself as someone whose policymaking and political experience at the Capitol would guarantee success in Harrisburg. To be sure, that was partly because she was running at a time when voter disdain for Washington and craving for managerial competence is running high. Plus her main rival, the Jeep-driving kitchen cabinet company rescuer Tom Wolf, sought to embody both business savvy and an outsider message.  

Just as importantly, Schwarz was seeking to sell herself to voters and donors who had never dealt with her before — the people who live in the 10 media markets outside Philadelphia and the 17 congressional districts other than hers, which covers both blue-collar city precincts and white-collar suburbs.  

Michaud, by contrast, has never been an inside player or a leadership darling — even while becoming a favorite of organized labor (he was a mill worker for three decades) and rising last year to the ranking spot on the Veterans Affairs Committee. Instead, Michaud has spent the past dozen years promoting the trade interests and transportation needs for constituents in one of Maine’s two House seats, a mostly rural 31,000-square-mile behemoth that reaches into all three of the state’s media markets.  

His name, if not his entire record, in other words, is familiar in most of the state. And getting exposure to the TV producers, board presidents, check-writers and other opinion-shapers across the entire state, history suggests, is more important than anything for someone who wants to move from the U.S. Capitol to a state capital.  

Of the House members who have tried and failed in the past 25 years, about half were bested in either primaries or general elections by politicians who were or had been in statewide office. That would be incumbent governors or lieutenant governors, secretaries of state, or current or former attorneys general. (At the same time, 5 of the 6 sitting senators who ran for governor were elected. The exception was Kay Bailey Hutchison, who retired two years after failing to oust Gov. Rick Perry in the 2010 Texas GOP primary.)  

In the 2010 midterms, only 4 of the 9 members elected to the 111th Congress were successful. And, it seems clear, that number was as high as it was because two of them gave up their House seats more than seven months before the election — so that they might spend all their time back home, trying to make news and raise money while exposing themselves to voters in the parts of the state that knew them least. And, today, both Democratic Gov. Neil Abercrombie in Hawaii and Republican Gov. Nathan Deal in Georgia are now safe bets to win second terms.