The fate of Ireland's government hung in the balance Friday as votes were counted to see if two historic rivals can join forces to shut out surging republicans Sinn Fein. Results from internal polls run by the centre-right Fianna Fail and Fine Gael, and their smaller Green partners, will reveal whether a deal has rank and file backing -- effectively approving or vetoing a new government. The final verdict on the pact is expected later Friday. A coalition deal would represent an historic compromise between old civil war rivals Fianna Fail and Fine Gael, longtime stalwarts of Irish politics. However, if blocked, Ireland faces another general election as it claws its way out of coronavirus lockdown, and a rerun of the February poll which saw Sinn Fein burst into the mainstream. The biggest concern for the deal is focused on the Green Party, which requires a higher standard of two-thirds majority approval from its members. Fianna Fail leader Micheal Martin is expected to be voted in as Taoiseach, or prime minister, in a special parliamentary sitting on Saturday if a deal is reached. As the head of Ireland's biggest party -- with 38 seats in the 160 seat chamber -- he will take the first turn as rotating Taoiseach under the novel terms of the deal. Incumbent Fine Gael leader Leo Varadkar -- whose party was routed to third place with 35 seats -- is slated to return to office later, reportedly taking the mantle in December 2022. Lete Thursday, Varadkar predicted the parties "will vote to go into coalition with each other". The Irish Times reported Friday that senior Green Party figures are "cautiously optimistic", but that two lawmakers expect a "tight result". The Green Party secured numerous flagship concessions in the coalition deal, wielding an outsized influence as a 12-seat bloc vital to bring the alliance over the threshold to command a parliamentary majority. But progressive party members have reason to be cautious of a deal with Ireland's centre-right establishment. After entering a coalition with Fianna Fail in 2007, the Green Party was wiped out in the ensuing 2011 general election, losing all six of its parliamentary seats. "There are risks for the Greens either way," University College Cork politics researcher Jonathan Evershed told AFP. If they decline to enter in the alliance "their role in holding the government to these environmental commitments will be minimised", he said. "But there's no guarantee if they do go in that they will be able to do that anyway." In a dramatic upheaval of the status quo, Ireland's February election saw republican party Sinn Fein -- historically associated with the paramilitary Irish Republican Army (IRA) -- leap to prominence. The one-time fringe party won the popular vote with 24.5 percent of first preference ballots, becoming the second-largest force in parliament after running on a left-wing platform. If the coalition government is formed, Sinn Fein expects to become the main opposition party. That could act as a vital foothold for the party in a push to power in the next election. "Being the lead party of opposition would suit them well, and I don't think they'd be too worried about a second election," Evershed said. "It's clear from some of the contents of the (coalition deal proposal) that Fianna Fail and Fine Gael in particular are very concerned about Sinn Fein, and have attempted to coopt some of their policies." However, the pandemic has improved the prospects of acting prime minister Varadkar's Fine Gael party, which bled seats in February after pinning its election campaign on success in the politically-tense Brexit negotiations. An Irish Times/Ipsos MRBI poll published last week showed Varadkar enjoying a 75-percent approval rating. Fine Gael on its own polled at 37 percent, improving their prospects in any subsequent election. jts/wai