WASHINGTON (AP) - House Republicans are feeling increasing pressure to steer firmly right on big issues because of changes in primary-election politics.
Those changes are making Congress more polarized and complicating its ability to solve big problems.
Independent research supports the belief by such lawmakers that they owe their jobs to GOP activists who have become more conservative over the years.
Many House Republicans say the key to their re-election is making sure no one mounts a viable primary challenge from the right. They say it's almost impossible for them to lose to a moderate Republican in a primary or to any Democrat in a general election.
House Democrats face a more liberal-leaning electorate in their primaries.
But Republican control of the House makes the GOP dynamic more consequential.