TAOISEACH Enda Kenny last night warned that Ireland would pay three times as much to borrow money if the country voted No in tomorrow's EU fiscal treaty referendum.
And a minister claimed that a No vote would cause "a run on the banks".
Making a final push for a Yes vote, Mr Kenny stressed that the question of future funding was vital and cautioned about the consequences of a No vote.
Only voting Yes would guarantee access to the EU's new bailout fund, he said.
Under the existing bailout, the Government is currently borrowing at a rate of about 3pc after being forced out of the international markets.
Mr Kenny maintained that by cutting off access to the ESM, the country would again be at the mercy of the rates on the markets -- where borrowing costs would be far higher.
"Countries that ratify this have access to the ESM, countries that don't won't and the difference between 3pc and 7pc or 8pc or 9pc is enormous in the context of availability of funding, were that ever to be necessary," he said.
The Taoiseach's claim that international investors also wanted the "certainty" of a Yes vote was backed up by the management of leading US multinationals.
Speaking at an American Chamber of Commerce event, executives from Hewlett Packard, Northern Trust, Microsoft and EMC all said the certainty brought about by a Yes vote would ensure investment continued.
EMC Ireland general manager Bob Savage said the expectation in the corporate headquarters of US multinationals was that Ireland would "participate actively" in the European Union.
Meanwhile, European Affairs Minister Lucinda Creighton claimed that a No vote would cause savers to flee Ireland's banks.
"We would have a major problem in terms of our banking system," she said.
"I do believe that there would be a run on the banks if we vote No. We've seen it in Greece, one billion a day -- so the evidence is there," she said.
Ms Creighton added that Ireland should be first in line to benefit if eurozone leaders gave the new bailout fund, the European Stability Mechanism, the power to rescue banks.
Meanwhile, Mr Kenny said he would not be "shoved around" by Sinn Fein after being accused of running scared from a television debate with Gerry Adams.
"I am not going to be shoved around by Sinn Fein," he said. "I am not going to give a platform to somebody who I don't regard as the leader of the Opposition to propagate what are blatant lies and hypocritical assertions."
Jobs Minister Richard Bruton rejected claims that Mr Kenny had refused to take part in a live TV debate because he and his advisers feared that he would make a mistake.
"The reality is that twice every week for the past six weeks, the Taoiseach has been answering questions (in the Dail) from those sources about the treaty," he said.
Fianna Fail leader Micheal Martin admitted that Mr Kenny should have participated in a TV debate -- although he also accused Mr Adams of having "ducked" a debate with him.