The world's 20 leading economies, the G20, piled pressure on Germany at the weekend to drop its opposition to a bigger European bailout fund, telling Europe it must put up extra money if it wanted more help from other countries.

But Merkel, leader of Europe's paymaster, first faces a difficult vote in parliament, which may force her to rely on opposition votes to approve the 130-billion-euro ($175 billion) rescue program for Greece, its second since 2010.

"Billions for Greece -- Stop!" Germany's top-selling newspaper Bild splashed across its front page.

"Don't go any further along this crazy path," the newspaper appealed, printing comments by leading economists as to why a default and temporary exit from the euro zone would be the better option for Greece.

In Monday's vote Merkel may be forced to rely on opposition support to overcome a determined band of rebels in her own coalition. She is due to lead the debate in parliament starting at 3 p.m. (1400 GMT), with the vote scheduled later in the day.

At least a dozen members of parliament in her centre-right coalition said they would vote against the rescue package. If the number of rebels rises to at least 20, the measure will pass only with opposition support.

That would be a humiliating defeat for Merkel, which analysts and opposition leaders said would raise doubts about whether her coalition could survive as well as her ability to cope with demands for an enlarged permanent bailout fund.

Merkel's allies are confident they have enough votes for a majority. The opposition Social Democrats and Greens have said they will vote for it.

Merkel needs 311 votes to reach a majority in the 620-member parliament. Her government commands 330 seats.

However, in a September 27 vote, 15 deputies in her coalition broke ranks, leaving the governing coalition with the narrow majority of 315 seats on that occasion.

GERMANS LOSING PATIENCE

An opinion poll published in a Sunday newspaper found 62 percent of Germans are against the rescue package while 33 percent are in favor. In a similar poll in September, 53 percent were opposed and 43 percent in favor.

One member of Merkel's cabinet, Interior Minister Hans-Peter Friedrich, openly called on Greece to leave the euro zone, saying its chances of recovery would be greater outside.

"Quite clearly the mood in Germany is turning against further rescues for Greece," Klaus-Peter Willsch, a leading dissident on Greek aid in Merkel's Christian Democrats (CDU), said in an interview with Reuters on Sunday.

"But that's not surprising. This is all deja vu for the public. We've been promised all kinds of things that aren't fulfilled and then a few months later there's the need for another rescue package. The public's faith is fading fast."

Germans, who are making the largest financial contribution to the euro zone bailout to Athens, are growing impatient with what Finance Minister Wolfgang Schaeuble described as a "bottomless pit" in Greece.

At the same time, there is a growing awareness in Germany, Europe's leading economy, that its own prosperity is at risk as the debt crisis sucks in more countries and stifles demand within the currency bloc for German exports.

German criticism of Greece has reopened wounds dating from World War Two. Protesters in Athens burned a German flag earlier this month while Greek newspapers have portrayed Merkel and Schaeuble in Nazi uniform.

Despite riding high in polls, Merkel has hit a rough patch - about 18 months before the next election - that has raised doubts about her grip on power.

Merkel is opposed to Greece leaving the euro zone, but her Bavarian allies, the Christian Social Union (CSU), face a difficult state vote in 2013 and have been raising the volume on calls for Greece to quit.

(Reporting By Erik Kirschbaum and Alexandra Hudson; Editing by Elizabeth Piper)

• A Permanent Economic Emergency