The deadline has passed for the US Senate to unanimously approve a bill giving Irish workers access to thousands of US visas every year.

It is understood Irish officials are now exploring other ways of securing support in the US Congress for a plan to add Ireland to the E-3 visa programme, which is currently only available to Australians.

In November, the House of Representatives voted in favour of the deal, but it needed to be passed unanimously by the US Senate.

One Republican senator, understood to be Tom Cotton of Arkansas, put a 'hold' on the bill and it failed to get approval before the outgoing Senate sat for the final time last night.

A new session of Congress will open today and Irish officials will continue their efforts to secure access to the E-3 visa programme.

Every year, more than 10,500 E-3 visas are offered to Australians who want to work in the US, but only around half of them are taken up.

Ireland wants to be able to access the remaining unused visas.

The Government is working on a reciprocal arrangement, which would ease restrictions on US citizens who wish to retire to Ireland and enable US citizens to work in Ireland on a similar basis.

E-3 visas are for two years, but can be renewed indefinitely. They allow the spouses of recipients to work in the US, but not their children.

In order to qualify applicants must be employed in a speciality occupation, have a legitimate offer of employment in the US and possess the necessary academic or other qualifying credentials.