WE’RE HAPPY TO accept Sen. Jim De­Mint’s stated reason for quitting the Senate seat he has held for eight years: to become president of the Heritage Foundation think tank. The South Carolina Republican says he’s moving on “because the conservative movement needs strong leadership in the battle of ideas,” and running Heritage is, for him, the way to provide it.

Among the thoughts Mr. DeMint has expressed as a senator include his observation that the 2008 financial rescue package that saved American capitalism was a step toward “the pit of socialism,” and his support for a constitutional ban on same-sex marriage.

But Mr. DeMint’s decision also may have consequences for the Senate, for the Republican Party and for the country. Mr. DeMint has been trying to leverage his position as the tea party’s uncompromising man in Washington into broader power over the GOP, and his resignation suggests that this effort has failed, or at least stalled.

With Republicans not having captured the Senate in November, as they once expected to do, Mr. DeMint has neither hope of becoming majority leader nor, apparently, of displacing his rival, Sen. Mitch McConnell of Kentucky, as leader of a shrunken minority.

Furthermore, there’s a case to be made that Mr. DeMint helped put the Senate GOP in its present predicament. To be sure, his political apparatus helped several of the Senate’s most conservative members win the seats they now hold, but he also backed candidates who were so far right that they lost winnable races and damaged the party’s brand.

We have no particular stake in the GOP’s electoral fortunes, much less its power struggles, which are undoubtedly just beginning. The party is still badly divided over how to recover from its 2012 defeat.

But everyone has a stake in a Senate whose members, of both parties, are neither ideologically inflexible nor politically cowed by the threat of primary challenges from the ideologically inflexible. Solutions to many of the nation’s problems, its fiscal challenge most of all, will require give and take. That’s true for substantive, as well as political, reasons. Republicans who don’t see compromise as a dirty word could both move their party in the right direction and better influence Democrats to give up some of their unsustainable orthodoxies.

From that point of view, Mr. DeMint’s departure may be a sign that a chastened GOP could shift in a more pragmatic direction on Capitol Hill — which is to say, it may be a hopeful sign.