* Election likely around October, centre left set to win

* PM Rusnok to resign on Tuesday, stay on as caretaker

* Markets ignore turmoil but 2014 budget in question

PRAGUE, Aug 9 (Reuters) - The Czech lower house of parliament will postpone a vote on its dissolution - which will open the way to an early election - to Aug. 20, from next Friday, to ensure enough deputies are present.

The house is likely to agree by a large majority to end its term more than half a year early, to overcome political deadlock that has crippled policymaking in the central European country.

Opinion polls show the centre-left Social Democrats likely to win the election, which could happen in October, by a double-digit margin, and return to government for the first time since 2006.

Petr Gazdik, head of the conservative TOP09 party's parliamentary group, said the dissolution vote would be moved to ensure the motion gets the 120 votes needed to pass in the 200-seat lower house.

"Friday is not the most common day for a lower house meeting," he said on Czech Television. "It's not like someone does not want to return from (holidays in) Croatia, but there are several deputies who have serious health or family issues."

Three parties - TOP09, the Social Democrats and the Communists - have said they would back the election plan. They have 122 seats between them.

On Wednesday, parliament voted against giving confidence to a government formed last month by non-parliamentary allies of leftist President Milos Zeman.

That government, led by leftist economist Jiri Rusnok, will formally resign on Tuesday, a spokesman said on Friday. It will stay in office in a caretaker capacity, possibly for more than two months until an early election.

Most political parties protested against Zeman's choice of Rusnok, saying the president was infringing on parliament's powers by picking his man without any agreement with parties.

Markets have been largely undisturbed by the deadlock because Prague boasts the lowest borrowing costs among central European countries thanks to its fiscal rigour and low debt load - half the European Union average. But the gridlock has clouded the formulation of the 2014 budget.

Rusnok's government replaced Prime Minister Petr Necas's centre-right coalition that crumbled in June under the weight of a spying and bribery scandal.

That coalition had asked for a chance to form another cabinet, but the Wednesday vote that rejected Rusnok also showed right-wing parties could not count on a reliable majority.

Several other deputies have said they would support the motion to dissolve parliament, and the largest centre-right coalition party, the Civic Democrats, also said on Friday that an election was the only way forward.

The Civic Democrats' popularity has slumped due to government austerity policies and graft scandals, and the party had until now opposed early election.

The Social Democrats speak in favour of higher taxes for utilities and high wage earners and support steps to prepare for adopting the euro.

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