Barack Obama's health care reform in doubt after Massachusetts vote

Analysis: Defeat for the Democrats in the special Senate election in Massachusetts has thrown President Barack Obama's health care reforms into doubt.

Victory for Scott Brown, a little known state senator, against the Democratic candidate Martha Coakley leaves Mr Obama one short of the key 60 Senate seats out of 100 he needs to prevent the Republicans from stalling legislation.

Now, barring the success of a charm offensive by the US President which could swing round moderate, wavering Republicans to support his party, he faces a protracted battle. The Republicans will be able to deploy the dreaded "filibuster" - the delaying mechamism under which they are able to debate legislation around the clock so that they render it impossible for the Senate to reach a conclusion.

Mr Brown has promised to use his vote to block plans to provide health care to almost all Americans, which the Democrats have been seeking for decades and Mr Obama was on the verge of delivering. Thirty million Americans are currently unable to afford health care.

One alternative option for Democratic leaders in Congress would be to ram through legislation before Mr Brown can take his seat. It has been filled in the interim by Paul Kirk, a former assistant to the late Senator Edward Kennedy - whose seat has fallen in Massachusetts - who would vote on party lines.

Though not against the rules, the negative political affects of disregarding the popular will in Massachusetts, especially given Mr Obama's pledges to clean up Washington, could prove highly damaging.

Another fallback plan could allow a moderate Republican senator such as Olympia Snowe of Maine to modify the bill as she wanted and then provide the 60th vote. Or negotiations could begin with numerous moderate Republicans who would demand even more changes.

The current most likely Plan B is for the House of Representatives to pass the version of the bill already passed by the Senate. This would avoid the process of reconciliation, in which separate bills already passed by each chamber of Congress would have been merged over the next few weeks.

But liberal Democrats in the House, where the party holds a large majority, were upset at various provisions in the Senate bill, and might decide no bill was a better option. Or some moderate Democrats, fearing for their seats at November's midterm elections, might abandon the health bill altogether after seeing a Republican triumph in strongly Democratic Massachusetts.

The Speaker, Nancy Pelosi, has repeatedly ruled out a House vote on the Senate's version but if Mr Brown wins then all bets could be off.