April 1 (Bloomberg) — The first phase of Obamacare ended yesterday much the same way it began: The federal website drew millions of visitors and crashed at least twice.

As the Patient Protection and Affordable Care Act moves into a new stage today, when most consumers must be insured or pay a fine, an estimated 45 million Americans remain uncovered, a continuing burden for medical providers and governments, and a target for Republicans seeking to upend President Barack Obama's signature initiative in the midterm election.

Still, Obamacare has survived with more than 6 million consumers signed up for private health plans and as many as 3.4 million people being added to the Medicaid program for the poor, according to the latest data. They'll start using medical services guaranteed by the law's strict mandates, even as some consumers complain about the high cost of their new premiums and insurers worry about a surge in older, sicker patients.