|Obama's healthcare reforms had faced strong opposition [AFP]
The US healthcare system is the most costly in the world and reforming it has been a high priority for Barack Obama, the US president.
The healthcare bill passed by the House of Representative on March 21 represents a big win for the president, but getting there has not been easy for Obama, elected in November 2008 with healthcare reform a major campaign pledge.
February 3, 2009: Tom Daschle, the former senate majority leader, looks set to spearhead Obama's healthcare reform bid, but he withdraws as the health and human services secretary nominee after revelations he was late paying income taxes.
Kathleen Sebelius, the governor of Kansas, is confirmed to the post in his place, but she lacks Daschle's Capitol Hill savvy.
March 5, 2009: Obama holds a White House forum to launch his reform effort, bringing together congressional, industry, union and think tank experts.
He vows to have a plan passed by the end of 2009, but the administration elects not to draft a detailed reform proposal, leaving that job to congress.
August 2009: Strong Republican and industry opposition mean congress fails to meet Obama's deadline of passing initial healthcare legislation by August.
Republicans oppose a proposal to create a new government-run health insurance programme, called the "public option" which would give Americans an alternative to private insurers.
Campaigners opposed to Obama's healthcare ideas confront Democratic lawmakers at "town hall" style meetings around the country, some denouncing the reform proposals as socialism.
September 9, 2009: In an address to Congress, Obama asks for quick action on healthcare legislation. One Republican lawmaker shouts "you lie" when Obama says his plan would not pay for healthcare for illegal immigrants.
November 7, 2009: The House of Representatives passes its version of healthcare reform legislation, including a public option, by a narrow 220-215 vote.
In the end, 39 Democrats vote against the bill and only one Republican votes for it.
December 24, 2009: The senate passes its bill on a party-line 60-39 vote. Democratic leaders muster the 60 votes needed to block Republican procedural hurdles.
They only manage it after making concessions, including a deal with Ben Nelson, a Nebraska senator, in which his state is exempt from expansion costs for the Medicaid insurance programme for the poor.
The senate bill has no public option.
January 19, 2010: Scott Brown, a Republican, wins a special senate election in the state of Massachusetts to replace Edward Kennedy, a veteran Democrat and champion of healthcare reform, who died of cancer in 2009.
This deprives Democrats of the 60 votes needed to end the Senate procedural hurdle known as a filibuster.
Democrats had been trying to merge the House and Senate bills into a single one that congress would pass again and send to Obama to sign. After Brown's victory, Democrats set aside that efforts.
February 22, 2010: Obama unveils his own healthcare proposal, drawn heavily from the senate bill, three days before a bipartisan summit intended to rescue his reform effort.
February 25, 2010: Obama presides over a bipartisan healthcare summit at Blair House, the presidential guest house close to the White House.
The meeting is marked by tense exchanges between the president and Republican opponents of his healthcare plans.
March 21, 2010: US House of Representatives approves a sweeping overhaul of the country's $2.5 trillion healthcare system and sends along for senate approval a package of changes made to the senate bill.