WASHINGTON - President Obama's health overhaul remains an all-consuming drama for many, even though millions of people are gaining insurance coverage through a law that's now five years old.

During oral arguments last week in the latest Supreme Court case brought by the law's opponents, Justice Elena Kagan called it a "never-ending saga."

Five reasons why the "Obamacare" epic plays on:

Political opposition. Unyielding opposition from conservative voters has made it practically impossible for Republican lawmakers to take a pragmatic approach to a program with obvious flaws, but also popular aspects.

Few want to go back to the days when insurance companies could deny coverage to people with pre-existing health conditions. But Republicans have followed a political game plan that requires them to first repeal Obama's law before trying to replace it with legislation of their own, presumably to accomplish similar goals.

A Supreme Court ruling invalidating the law's subsidies in most states would give Republicans their best opening yet. But any "replacement" legislation also would spend taxpayer dollars and spawn new federal regulations.

Administration stumbles. The president who once said you could keep your health plan if you liked it was caught flat-footed by a wave of insurance cancellations blamed on health law requirements taking effect in 2014.

The HealthCare.gov website, talked up as the equivalent of Amazon and Travelocity, broke down the day it was launched in 2013, and took months to patch up.

That same year, the administration announced the delay of a major requirement affecting employers on an obscure government blog just days before the Fourth of July.

This year, HealthCare.gov sent the wrong tax information to about 800,000 people, and an online insurance market geared to small businesses has disappointed.

Unconventional path to passage. The Affordable Care Act did not get the legislative equivalent of close editing by a House-Senate conference committee.

Congressional committees worked on different pieces of the bill and the complete package was assembled in negotiations shepherded by leadership.

That could have made it more likely that glitches would get baked into the 900-plus pages of the law.

Costs of care. Although premiums are heavily subsidized, people who buy private coverage through the law's insurance markets may still struggle with costs.

Out-of-pocket expenses, including the annual deductible and required copayments, can be as high as $6,600 for an individual and $13,200 for a family.

It's complicated. Obama's law joined two of the most complicated areas for consumers: health insurance and taxes.

Even now, in the second year of coverage, enrollment counselors say many consumers get overwhelmed trying to understand what plan is best for them. It can be hard to figure out which doctors are in what plans, and what the patient's share of the cost for a particular medication is.

This tax filing season will reveal the connections between the law and the tax system, which is used to deliver carrots and sticks.