The Founding Fathers didn't expect that serving in Congress would be a lifetime career. And for a century, it mostly wasn't. The first election in which more than half the incumbent members of the House of Representatives were reelected was in 1898. Since then, a majority of House members have been returned in every election except 1932.

That's the context in which to weigh the fact that three incumbent Republican House members who have been comfortably reelected have recently announced they are retiring — and the rumors that more will do so. Incumbents tend to know, and be known in, their districts. They usually win, while open-seats contests often result in changes of party control.

The three retiring Republicans are seven-termer Dave Reichert of Washington 8, seven-termer Charlie Dent of Pennsylvania 15, and two-termer Dave Trott of Michigan 11.

Reichert was reelected 60-40 in 2016 in a district dominated by affluent eastern Seattle suburbs, plus some Republican farm country east of the Cascades. Donald Trump lost the district 48-45, a little worse than Mitt Romney's 50-48 loss.

Dent was reelected 58-38 in a district that includes the industrial and suburban Lehigh Valley around Allentown. Trump carried the district 52-44, a bit better than Romney's 51-48 finish.

Trott was reelected 53-40 in a district in the western Detroit suburbs. Trump carried that district 50-45, and Romney won it 52-47.

So, all three ran ahead of Donald Trump in closely divided districts. Demographically, Pennsylvania 15 is tilted to non-college whites, among whom Trump ran stronger than traditional Republicans; Washington 8 and Michigan 11 are tilted to white college graduates, among whom Trump ran behind Republicans like Romney and George W. Bush.

Democrats have been running ahead of Republicans on the generic vote question — which party's candidate will you support for the House of Representatives? — by 46 to 37 percent in the realclearpolitics.com average. That sounds big, but in the past the generic vote has tended to overstate Democrats' support, and an unusual percentage chime in as undecided. Also, the clustering of Democratic voters in relatively few urban and university districts means the party could win the House popular vote but still fall well short of a majority, as it did in 2012.

But as Real Clear Politics analyst David Byler has noted, the Republican generic numbers have been tracking close to the Trump approval rating. That's risen just a bit during hurricane season, but is still underwater in post-Labor Day surveys, at 40 percent approval, 56 percent disapproval. His favorable/unfavorable numbers are negative too, but they were similarly negative last November 8.

The nightmare scenario for House Republicans is that their candidates, especially in open seats, run no better than Trump in high-education districts and no better than traditional Republicans in low-education districts. That's roughly what happened in the four seriously contested special elections this spring. That puts at risk the 241-194 majority Republicans won in 2016.

The nightmare scenario facing Republicans like Reichert, Dent, and Trott is that they get opposed by Trumpish (or Steve Bannon-ish) or tea party type Republicans in their primaries and by well-financed Democrats who have been lining up to seriously contest the general.

Plus, the reward for winning is coming back to a House Republican Conference split between leadership loyalists and the Freedom Caucus, and dissed and possibly spurned by Trump. Trump and the Freedom Caucus types share a corrosive distrust of Speaker Paul Ryan, but their views on important issues are often wildly divergent.

House Republican rebels insist on purism and are oblivious to the history that legislative majorities, if they stick together, can move policy significantly, but not totally, in their direction, absent a crisis equivalent to the Civil War or the Great Depression.

House Democrats, like Henry Waxman expanding Medicaid, did this even in the Reagan years. But not by preventing the party's House leadership from amassing majorities for the basic tasks of governing.

Republican incumbents may be choosing to retire to avoid harsh competition in primaries and in November. But they may also be motivated by something verging despair that their party seems likely to fall far short of what it might reasonably have been expected to accomplish with the presidency majorities in both houses of Congress.

In those circumstances, they seem to be behaving as the founders expected and as politicians routinely did until 1898: pursue other endeavors and let someone else endure the frustrations of trying to govern.