European officials sought to deflect mounting pressure from world leaders about the region's debt troubles, warning of a long road ahead to end the crisis.

Heads of the Group of 20 advanced and developing economies, which opened their meeting here Monday, offered cautious hope about election results in Greece, which could help the nation stay in the euro zone. But leaders quickly moved on to broader worries in the 17-nation currency union as Spain faced new market pressure.

President Barack Obama said Greece's Sunday election 'indicates a positive prospect' for the country to work with its international creditors. He said leaders at the G-20 would work on plans for supporting the economy and doing 'what's necessary to stabilize the world financial system.'

German Chancellor Angela Merkel cast doubt that Greece would get more time to meet its commitments. Other officials also suggested Greece could get some help to boost growth, under broader measures Europe is considering across the continent. 'It is more important that the new government stick to the commitments that Greece has made to the international community and its partners in the European Union,' Ms. Merkel said.

The crisis in the euro zone again was set to dominate discussions among world leaders gathering in this Mexican resort. While leaders didn't expect to make major decisions here, many hoped the summit would help European leaders make concrete moves at their own gathering at the end of next week.

But the Continent's leaders maintained that bigger leaps in euro-zone integration would not be swift.

European Council President Herman Van Rompuy said leaders expected to have proposals for a banking union, to consolidate supervision of financial institutions across the continent, by this fall. Other steps toward unifying the continent's budgets could require up to a decade to secure approvals from the 27 democracies across Europe.

'Reforms take time,' he said. 'We are patient. We understand this is not an easy task... We will overcome--step by step, slower than we expected--but we will overcome our problems.'

Countering hopes from other leaders and investors, Mr. Van Rompuy said, 'the pace is less important than the decision we make.'

As yields on Spain's 10-year debt surged above 7%, the country's top economic official maintained that markets would back off over time.

'We're convinced the current penalization by markets doesn't reflect our efforts, or the potential of the Spanish economy,' Finance Minister Luis de Guindos said. 'We're convinced that, with the reforms we've carried out and the ones we'll carry out, and the move toward financial union in Europe, the market situation will correct itself.'

The continent is coming under intense pressure from markets--and world leaders--to implement their next moves more quickly. Each of their moves is seen as too little to get ahead of investors' worries that the currency union will break apart, sending shock waves through global financial markets.

'The European decision-making process is really slow--designed for process, not decisions,' said Guillermo Ortiz, a former Mexican central banker. 'Until the markets see certainty--a roadmap that is going to get them from A to B--they won't react positively to events.'

European officials, bracing for criticism from world leaders at the summit, quickly countered that other problems are also helping to drag down the global economy.

'We are not coming here to receive lessons and in terms of democracy or in terms of how to manage our economy,' said European Commission President Jose Manuel Barroso.

'We are not complacent about the difficulties,' he said. 'We are extremely open and engaging...We are certainly not coming here to receive lessons.'

Sudeep Reddy / David Luhnow / Carol E. Lee