The Republican push to replace the Affordable Care Act was revived this week in Congress by a small change to their plan designed to combat concerns over coverage for those with pre-existing health problems.

The change helped get the bill through the House of Representatives in a tight vote Thursday, but experts say it may make little difference in the hunt for affordable coverage for these patients.

The bill proposes setting aside an additional $8 billion over five years to help states cover those who may be subject to higher insurance rates because they've had a lapse in coverage. That's on...