What was required to pass this?

In order to be signed into law by the president, the Senate must pass an identical version. If the Senate passes a version that differs from the House version - both houses must negotiate to arrive at a common bill - which then must pass both houses.

The American Health Care Act passed in the House of Representatives on May 4, 2017.

The Senate's original version of this bill became inactive after Senate Republicans could not obtain enough votes to pass it.

Senate Republican leaders then renamed it to the American Health Care Act - to match the name of the House version and passed a motion to proceed to accept amendments.

The major "amendments" effectively were full bills by themselves - as they replaced the entire contents of the version passed by the House with a version written by various Senate Republican leaders.

This attempt to repeal Obamacare is dead

The final such amendment was the Graham-Cassidy amendment.

Senate Republicans had until Sept. 30 to pass a version of the bill. That was the final day of the federal government's 2017 fiscal year, and the last day on which they could have used the special budget reconciliation process to pass the bill without it being susceptible to a filibuster.

It also was before the Congressional Budget Office (CBO) was expected to complete its estimate on how many people would have lost insurance - or the cost to those who kept it.

On Sept. 26, Senate Republicans pulled the bill from consideration because it did not have enough support to pass.

Note: The Senate could attempt this again with a new reconciliation bill, but they intend to use the process in the 2018 fiscal year to rewrite the country's tax laws.