By Martin Santa

BRATISLAVA (Reuters) - Slovakia's ruling coalition will have to reallocate cabinet posts or face a snap election unless it can find its own majority in parliament for a crucial vote on the euro zone's rescue fund, the main opposition party Smer said on Sunday.

The euro zone's second poorest country of 5 million people has become a major risk to the bloc's July deal to give the European Financial Stability Facility (EFSF) more power to tackle the crisis threatening its weaker debtor economies.

The center-right coalition of Iveta Radicova is struggling to win enough support in parliament for the EFSF vote, which is due by October 14, because junior partner Freedom and Solidarity (SaS) has so far refused to support the measure.

"Either this government approves the EFSF and the coalition will do so by itself, or the ruling coalition will not be able to make such a decision and it will have to make it with the help of the opposition, but with consequences for the functioning of this ruling coalition," Robert Fico, leader of Smer, said in a debate on Slovak Television on Sunday.

Smer, leading all opinion polls by a wide margin with public support close to 40 percent, supports the EFSF but refused to help out the coalition, which Fico said must change the allocation of cabinet posts or call a snap election if it fails to unite.

"We are ready to support the EFSF, but if we do so, it means there is no ruling coalition in Slovakia," said Fico, Radicova's predecessor as prime minister.

Radicova, in power since July last year, said on Friday she would meet with SaS leader Richard Sulik this weekend, before Tuesday's meeting of all coalition leaders.

No meeting took place on Saturday and SaS said no meeting with Sulik and Radicova was planned for Sunday.

Slovakia is one of the three remaining euro members which need to approve a wider mandate for the 440 billion euro ($590 billion) EFSF so it can make emergency loans, rescue banks and help governments whose bonds come under market attack.

Pressure on Slovaks rose on Friday when Slovakia's European Commissioner, Maros Sefcovic, rapped Radicova's government for delaying the latest efforts to resolve a crisis economists fear could trigger a new global downturn.

SaS of seeking to boost its popularity rather than trying to compromise with partners and unlock the ratification process.

"No ruling coalition can function if one partner says 'not me' and we go on. We can't go on," Bugar said.

Radicova made a proposal to SaS earlier this week that SaS said created room for compromise, but an embargo is in place until the party delivers its reaction.

"We are not seeking to change EFSF rules," Bugar said. "The compromise solution will allow Slovakia to vote on every (EFSF) loan, every use of (EFSF) funds."

Bugar, however, declined to elaborate on details of the mechanism and how Slovakia might secure such a concession.

($1 = 0.745 Euros)

(Reporting by Martin Santa; Editing by Ruth Pitchford)