Lobbying efforts went to the wire ahead of today's announcement of the host country for the 2023 Rugby World Cup.

Government and sporting officials conducted a final round of phone calls in the hope that Ireland could force a run-off with South Africa.

Two separate Cabinet sources yesterday said a decision was taken at Government level to pursue the lobbying efforts to the finish line.

Irish hopes rest on the fact that if South Africa fails to secure 20 votes, the third place team - likely France - will be eliminated. In this scenario, a second vote would be held.

Ireland would then be given leeway to embark on a fresh round of lobbying in a bid to secure the support of the countries that leant their support to the French.

One Cabinet minister directly involved in the process said last night that the Government is resigned to the fact that the prospect of landing the 2023 event appears "extremely difficult". A separate source defended Ireland's bid, saying an "uphill battle" was posed by the fact that the initial technical assessment came down heavily in the favour of South Africa.

Sports Minister Shane Ross and Junior Minister Brendan Griffin were due to travel to London today for the announcement, scheduled for 1pm.

Mr Ross was present at Ireland's World Cup clash against Denmark at the Aviva Stadium last night.

But the majority of the lobbying has been overseen by Taoiseach Leo Varadkar and his officials, according to well-placed sources.

Behind-the-scenes conversations have taken place with both British Prime Minister Theresa May and Scottish First Minister Nicola Sturgeon with Government sources saying they are confident of securing their support.

"A particular effort was made to woo the Scots," said a source.

As previously revealed by the Irish Independent, Mr Varadkar was keen to enlist a network of ambassadors as part of the lobbying bid.

But there is the strong view within Government circles that World Rugby is strongly in favour of South Africa landing the tournament.

Both Ireland and France wrote to World Rugby criticising the manner in which the evaluation report scored South Africa in terms of stadiums.

Last week, Mr Ross said many stadiums in South Africa are so large they will be more or less empty for some of the minor matches - in stark comparison to Ireland.

"I'm unhappy with the comparisons made with the South African stadiums.

"Because the South African stadiums are very, very large. And they are going to have, obviously for minor matches, they are going to have empty stadiums."