FILE PHOTO: Sinn Fein souvenirs on sale before a public meeting Liberty Hall in Dublin, Ireland February 25, 2020. REUTERS/Lorraine O'Sullivan

DUBLIN (Reuters) - The pro-Irish unity Sinn Fein party would easily win a repeat Irish election if ongoing government talks fail, with an opinion poll on Saturday showing it has almost twice as much support as its two nearest rivals.

The left wing party’s support jumped to 35%, ahead of Fianna Fail on 20% and acting Prime Minister Leo Varadkar’s Fine Gael on 18% in a Sunday Times/Behaviour & Attitudes poll that may influence early talks between the two centre-right rivals.

Sinn Fein shocked the political establishment in an election earlier this month by securing more votes than any other party for the first time, almost doubling its vote to 24.5%, ahead of Fianna Fail on 22.2% and Fine Gael on 20.9%.

But it has been frozen out of government talks by its two rivals, who refuse to contemplate sharing power due to policy differences and Sinn Fein’s history as the political wing of the Irish Republican Army, the militant group that fought against British rule in Northern Ireland in a conflict in which some 3,600 people were killed before a 1998 peace deal.

Caught by surprise themselves, Sinn Fein ran too few candidates to emerge with the most seats - a mistake it will not make next time around. It has already begun a series of packed national rallies to sure up its support.

Both Sinn Fein and Fianna Fail have 37 seats in the fractured 160-seat parliament, with Fine Gael on 35, meaning some sort of combination of two of the three largest parties is required to form a government.

Bruised by its election defeat, Fine Gael will reluctantly hold a “one-day policy exchange” with Fianna Fail next week as well as similar talks with the Green Party, whose 12 seats would be needed for the two historic rivals to reach a majority.

If Ireland’s two dominant parties cannot agree to lead the next government while also maintaining their steadfast opposition to governing with Sinn Fein, a second election would be the only way to break the deadlock.

All sides predict talks will take a number of weeks before such a choice has to be made.