A final vote on immigration reform in the US Senate last night failed to gain a majority in favour of moving the legislation forward.

It is being seen as a major legislative setback for President George W Bush who had backed the bill.

For many of the millions of illegal immigrants in the US, including tens of thousands of Irish, this bill represented the best opportunity for comprehensive reform in years.

Immigration reform is arguably the biggest and most contentious domestic issue in the US and senators on Capitol Hill have battled over the past two weeks to shape their version of this crucial legislation.

Originally billed as a grand bargain bringing together Republican and Democratic senators as well as the President, the bill fell victim to several amendments from both sides of the aisle which eroded its core base of support.

A final vote last night was 15 votes short of the majority needed to move the legislation forward.

The Senate Majority Leader Harry Reid has now shelved the legislation.

While its supporters believe it can be revived, the upcoming US Presidential elections means that time is not on their side.

Afterwards one of the bill's architects, Senator Ted Kennedy, said while the vote was a big disappointment, failure was not an option.

He said he intended to continue to work for the bill to become law.