House Republicans feel growing pressure to steer firmly right on key issues, thanks to changes in primary-election politics that are complicating Congress’ ability to solve big problems. Independent research supports the belief by these lawmakers that they owe their jobs to increasingly conservative activists, and that it’s safer than ever to veer right on many subjects rather than seek compromise with Democrats. On the flip side, House Democrats face a more liberal-leaning electorate in their own primary elections. But the trend is less dramatic for Democrats, whose supporters are more open to compromise to help government work, polls show. And...
